After the trauma of their recent experience with the Krotons, the Doctor and Charley are enjoying breakfast at Al’s Café. Charley is in danger of falling asleep at the table, but the Doctor thinks she’ll feel better once she’s eaten something. She’s impressed that the TARDIS brought them exactly where he said it would and says this is the first trouble-free trip she’s had with him. She makes a fleeting reference to her mother, which prompts the Doctor to ask if she can remember her mother’s name or date of birth, but she says she still can’t remember. The Doctor glances at a discarded newspaper and then suddenly announces that as soon as they’ve finished breakfast they need to go straight to Manchester…

DI Patricia Menzies and her team are engaged in a police stake-out at some flats in Manchester. Menzies assigns positions to her officers to make sure their suspect doesn’t sneak out before they’ve had a chance to arrest him. She hopes he’ll come quietly, but their profile on him suggests he’s likely to be on edge. Then, to her surprise, a huge man arrives on the scene, knocks out one of her officers and then demands she hand over the key to flat 12. When she resists, he grabs it from her and lets himself into the flat. In the room, the suspect refuses to go with the huge man and says he knows what Brooks has planned for him. The huge man tries to take him by force and mocks the suspect’s attempts to warn him off. Another officer arrives outside the flat with another spare key, but before they can enter, they hear a scream and the sound of breaking glass. Menzies and the others rush inside and discover the suspect has escaped out the window and the huge man has a fatal puncture wound to the heart which appears to have happened when he fell into a mirror.

Back at the station, the police still don’t know who the dead man is, but Menzies thinks their priority should be tracking down the suspect. According to eye witness reports, his face and hands look rough and grey, as if he has some kind of a skin condition, so he’s unlikely to be able to keep a low profile. Unfortunately it’s Christmas and the weather is cold, so everyone’s going to be wrapped up in hats, gloves and scarves. Menzies is informed that some visitors have been waiting to see her for over an hour, and she’s amazed to see that it’s none other than the Doctor and Charley.

She takes them to an interview room to get some privacy and the Doctor asks her if she read the story in this morning’s newspaper. It tells of Martin Jones, a man from Manchester, who discovered a pound coin in his change which appears to have come from the future. He got it from a ticket machine at the railway station when he noticed it had the year 2012 printed on it. The fact that the story appears in a tabloid newspaper with an extremely dubious reputation doesn’t help convince Menzies, but the Doctor says the coin featured in the photograph is genuine. Menzies realises for the first time that he and Charley are time travellers and is surprised they didn’t bother mentioning it the last time they met. However, she also admits they’re not the first time travellers she’s encountered. The Doctor says he needs her help as he’s concerned about whatever else the owner of the coin might have brought back from the future. They might be trying to change the course of history or weaken the Earth for an attack, and even if they’re harmless it could be disastrous if they don’t know what they’re doing. Menzies agrees to help and the Doctor asks if they can look back over the CCTV footage from the railway station, claiming he has the means to examine it in far more detail than she could.

In the meantime, Menzies thinks one of her informants might be able to help and she invites Charley to join her. In the car, she explains that Kelsa McArthur is an alien time traveller who she met after word got out about her assistance in the Shinx case. The police obviously don’t know anything about it, but aliens have started coming to her for help and in return she makes sure things stay low-key. Unfortunately she’s now being bombarded with requests, but at least she sometimes gets them to do things for her in return. Kelsa, for example, is able to sense disturbances in time, so he might be able to help them track down their mysterious time traveller. Menzies wonders whether they might be wasting their time and it’s possible the Doctor might have brought back the pound coin from 2012 himself without even realising, or possibly he might do it in the future - in which case, their investigation may end up with the Doctor meeting his future self. Charley is impressed as Menzies has a pretty good grasp of the complications of time travel.

At that moment, someone else is also seeking help from Menzies’ informant. Kelsa’s visitor is asking about a Shinx called Kord who was living in the area under the name of Gregory Bailey. Kelsa thinks he might have the number for the man’s wife Antonia, but when they try to call her, the number isn’t recognised. The visitor asks for help in getting away, but although Kelsa sympathises, he can’t afford to get mixed up in things. Menzies rings the flat to warn Kelsa she’s on her way over, so he asks his visitor to leave and make sure no one seems him. The man assures him he’s very good at not being seen, which is just as well with a face like his…

A young woman named Carmen receives a phone call, warning her that they won’t be able to leave now until later afternoon in the earliest as they have engine problems and experts in such things are a bit thin on the ground here. She says there’s a place she wants to go to this evening if they have time and the man on the phone asks if she’s won enough to cover her book while she was ashore. She promises he won’t have to put her on dish-washing duties.

Menzies and Charley arrive at Kelsa’s flat, but as soon as he meets Charley he starts to get a headache. The pain becomes really intense and he has to ask her to step back while he takes some dampening medication. Menzies assumes it’s because Charley is a time traveller, but Kelsa says it’s much more than that - her timeline is all snarled up in an unresolved paradox. He realises she’s close to someone she’s already met in his future, but when he meets her later it’ll be in her past. Charley confirms that Kelsa is absolutely right and she pleads with Menzies not to tell the Doctor as it’s vital for his own good that he doesn’t find out. Menzies becomes suspicious of Charley, but she assures her she’s not up to anything. Kelsa recovers and says he can see Charley properly now. Menzies receives a call about another alien who needs her help, so she asks Charley to stay here and question Kelsa while she deals with the other matter.

Charley tells Kelsa that she and the Doctor think there might be a time traveller somewhere in the city recently. Kelsa says that apart from the temporal disturbance caused by their own arrival this morning, it’s been quiet here recently. He tells Charley that he’s encountered people with similar circumstances to her own - in fact, it’s an occupation hazard for time travellers - but her particular situation is much more dangerous than usual. He advises her to tell the Doctor as it could cause a serious problem, but he can’t be more specific until his dampening medication wears off and he’s not looking forward to that as it will be extremely painful for him. He agrees to help, but only if she promises to tell the Doctor the truth. She says she can’t do that, but he warns her the timeline “hates” her presence here and if she won’t tell him, then he will…

Menzies phones the Doctor at the police station and tells him one of her ‘contacts’ has reported a dead alien and she’s on her way to investigate. He joins her at a residential address and she shows him the body. The owner of the house, who Menzies has nicknamed ‘Sparky’ because he looks like football manager Mark Hughes, has reverted to his natural gaseous state because of the stress, but he eventually re-forms back into a humanoid form. Judging by the height of the body, the uniform and the orange skin, the Doctor identifies the dead alien as one of the Tabbalac. They’re an aggressive species who are noted for their matter transmission technology. They’re also very good at reading body language and always know when someone is lying, but the Doctor thought they were virtually inactive in this time zone. According to ‘Sparky‘, the Tabbalac broke into the house while searching for someone, but then another man appeared from nowhere, they had a fight and then the victim was killed.

When the body is collected by some more of Menzies’ contacts - aliens who have matter converter technology - the Doctor starts to realise what an effective network she’s got working with her. Unfortunately she can’t file any official reports on this sort of thing, so she has to work overtime just to make progress on her genuine police cases. The Doctor sympathises, but says she must be building up a list of useful contacts and one day they might be able to do her a favour in return. As they travel back to the police station, he tells her his own investigation is coming along very well. By cross-referencing the ticket machine data with the CCTV footage, he was able to identify the owner of the future coin, then he followed it back until he eventually discovered that the waitress at the Japanese restaurant Takeshi’s had received it as a tip from a woman who dined there the night before. The Doctor’s next step is to identify the unknown woman, so he asks Menzies to drop him off by the TARDIS where he can pick some equipment up. Inside, he discovers the ship has activated its Hostile Action Displacement System. Confident there’s nothing unusual going on, he switches it off and starts looking for a type 7 enhancer for his etheric beam locator and a nice warm scarf.

Menzies returns to Kelsa’s flat and finds Charley standing at the top of the stairs, with Kelsa lying dead two flights below her. Charley explains that he went outside to investigate someone moving around, but by the time she joined him he‘d fallen. Menzies is sure this was no accident and asks Charley why she didn’t call her when it happened. Charley says it only happened a minute ago, but there’s no evidence of anyone else here apart from Charley. As Kelsa had mentioned that Charley desperately wanted to keep something from the Doctor, Menzies has no choice but to arrest her on suspicion of murder.

The Doctor tells the Tabbalac he’ll be happy to co-operate if he can give him a more comprehensive explanation, but then another alien from a different species arrives and orders the Tabbalac to stop what it’s doing. The Tabbalac insists that the Doctor is harbouring a traitor, but the new alien says this is irrelevant and orders him to stand down. The Tabbalac refuses and starts shooting, but after a short exchange of fire, the Tabbalac himself is the only one killed. The new alien checks that the Doctor is unharmed, then it disappears before he can ask it any questions.

The young woman named Carmen receives another phone call, warning her it’ll still be another few hours before they’re able to leave. The man on the other end is keen to get away as soon as they can as they’re already missed appointments in two cities.

The forensic team arrives at Kelsa’s flat and Menzies orders Charley to get in the police car so she can be taken back to the station. Charley doesn’t know how she can prove her innocence and she assures Menzies that Kelsa’s death was just an accident, but Menzies advises her to be quiet. They decide to take a detour as the roads ahead are packed with Christmas shoppers - but then suddenly another car pulls out in front of them. Menzies swerves to avoid hitting it, but they crash into a wall and Menzies is knocked unconscious. To Charley’s amazement, a man climbs out of the boot of the police car and tells her to follow him. Charley is reluctant to leave, but the man says he knows she’s innocent of the murder and eventually he convinces her to join him. He introduces himself as Lish and they flee just as Menzies starts to come round. Moments later, the Doctor arrives on the scene and checks that Menzies is alright. He calls for an ambulance, then Menzies tells him what happened and reveals that she’d arrested Charley on suspicion of murder.

Lish takes Charley to a derelict building nearby where they should be safe. He tells Charley he saw what happened back at Kelsa’s flat, but he couldn’t tell the police as they’ve already wrongly blamed him for a couple of deaths in the past. He says he hid in the boot of the police car so he could follow Charley as he didn’t want the same thing to happen to her. She asks him if he caused the car crash, but then she realises this is a stupid thing to suggest. Lish is disappointed when she tells him she’d only met Kelsa today for the first time, but fortunately she has previous experience with aliens, so she’s not disturbed by his appearance. Lish says he’s looking for somebody called Kord, who went under the name of Gregory Bailey, and Charley says she met him earlier in the year but he’s dead now. Lish is devastated and reveals that some people are after him and Kord was the only person who could help him. Charley is sure the Doctor will help Lish, but as he’s working closely with the police at the moment she suggests going back to the TARDIS and waiting for him there. Unfortunately, the ship doesn’t seem to be where she thought it had landed and it soon becomes clear the TARDIS has gone!

The Doctor takes Menzies to the hospital so she can be checked out, but she suspects he’s just trying to keep her occupied so she won’t have time to go after Charley. The Doctor insists that the notion of Charley being a murderer is completely unbelievable and says he’ll vouch for her. He also warns Menzies there are more Tabbalac in the area as he was attacked by one earlier. He tells her he was able to track down the woman who left the pound coin as a tip at Takeshi’s restaurant. Her name is Carmen Preminger and she had it in her possession when she arrived in Manchester via a boat two days earlier. Since then she’s been staying at the Palace Hotel and has been seen frequenting various casinos in the area. The Doctor suspects she’s been abusing time travel in order to defraud those establishments and he intends to stop her. Menzies thinks it all sounds a bit trifling compared to everything else that’s going on, but he argues it could be important. Menzies says she still needs to find Charley and threatens to have him charged with obstruction if he won’t help, but the Doctor insists he has no idea where she is or what her motive for the murder could possibly be. He refuses to be threatened and says he plans to find Carmen and follow her to whatever casino she’s planning to visit tonight. Menzies reluctantly agrees to let him go, but gives him a phone so she can keep in touch.

It’s not long before the Doctor finds Carmen waiting to be served at the bar in one of the city’s casinos. He casually begins making conversation, but then the barman brings him a drink and says it comes with the compliments of a lady sitting in a nearby booth. He’s not surprised to find it’s Charley, who’s been following him for some time. She assures him she wasn’t responsible for the death of Kelsa, but he already believes her and can’t understand why Menzies has suddenly become so suspicious of her. She admits that she panicked after the car crash and was helped by an alien who has problems of his own. She then reveals that the TARDIS has gone and he remembers that the Tabbalac who attacked him earlier wanted to get inside, so his colleagues probably came back for it. He warns her they can’t be seen together as Menzies will be expecting Charley to make contact with him, so he arranges to meet her tomorrow evening at the Night and Day Café.

As she leaves the roulette table with her winnings, Carmen bumps into Lish and she says she’s surprised he’s been allowed to leave the ship. He asks her where Brooks is, but when she tells him he’s still aboard, he makes an excuse to leave. He then rejoins Charley who tells him the Doctor recommended they leave. Carmen then takes her place at the poker table and is joined shortly afterwards by the Doctor, who claims he’s just come to watch. He asks her what her strategy is, but she refuses to discuss it and tells him he’s distracting her. However, when the cards are called, she’s amazed to discover that she hasn’t won and she angrily accuses the Doctor of secretly working for the House and deliberately putting her off her game. She physically grabs him and throws him to the floor. She demands that he pay her back, but just when it looks like things are going to turn violent, the police arrive, headed by DI Menzies. The officer confronts Carmen who accuses the Doctor of rigging the game, but Menzies ignores her and has her arrested. The Doctor thanks her for coming to his aid, but she admits she only came here in response to a tip-off that the murder suspect was seen here. While her team search the premises, Menzies agrees to help the Doctor question the alleged time traveller.

Charley decides to take Lish to Ackley House as she has a couple of “friends” there. Lish agrees, so long as it’s nowhere near Salford Quays as that’s where they’re trying to take him. He says there’s a ship moored there called The High Straights and Carmen, the woman they saw at the casino, is one of a handful of residents who live aboard it. Charley tells him the Doctor was interested in Carmen’s recent activities, but Lish warns her she can’t remember anything further back than a year. Suddenly two police cars approach them from different directions, so they race down an alleyway and start to climb over a gate. One of the police officers grabs hold of Lish’s leg - but then he lets go and falls from the gate for no apparent reason.

Carmen is being questioned by the Doctor and Menzies, but she realises they’re not following normal procedure as the interview isn’t being recorded and she hasn’t been offered a solicitor. She believes she’s being held for assaulting the Doctor and assumes he must have been an undercover police officer, but the Doctor tells her he suspects her of abusing time travel in order to defraud the casinos. Carmen appears to be genuinely shocked and doesn’t know what to say, but the Doctor suggests she’s been very successful in all the local casinos over the last two days because she’s been here before and watched the roulette wheels. Carmen points out that most of her money is won at poker and it’s simply because she happens to be very good at it. The Doctor decides to test his theory with his etheric beam locator, but it doesn’t work and Menzies is so embarrassed she cautions Carmen for attacking the Doctor and then lets her go. When they’re alone, Menzies points out that they have no evidence against her and as she’s a poker player she’s unlikely to crack up and admit the truth. Then Menzies reveals that Charley was spotted going into the same casino earlier and the Doctor is forced to admit that he saw her there briefly. The Doctor then changes the subject and decides to follow Carmen in order to gather more evidence against her. Once he’s gone, Menzies calls another officer and asks him to follow the Doctor discreetly.

Charley and Lish have shaken off the police and stop for a rest, but Lish is keen to get moving again quickly and Charley is the only one who knows where they’re going. Lish is starting to realise how much he’s grown to like Charley, but she doesn’t think they have time for that sort of thing. Just then, two huge men dressed as bouncers arrive on the scene and knock them both out, then they pick up Lish and carry him away…

Back at the police station, Menzies receives a call back from her officers to say that they’ve found Charley unconscious in the street. Charley comes to the phone and groggily explains what happened and remembers that Lish had told her his pursuers wanted to take him back to Salford Quays. Menzies decides to go down there and asks Charley to join her.

The Doctor is in a taxi following Carmen in another taxi when Menzies rings him. They’re moving in the direction of Salford Quays and Menzies reveals that she’s also heading in the same direction. The Doctor tells her he easily managed to shake off the policeman who was following him, but Menzies thinks that’s a shame as it appears that their alien murder suspect is being taken there too.

The two bouncers arrive at the Quays and report to their boss, Brooks, but while they’re distracted, Lish manages to release himself from the car and disappears before they can stop him. Brooks angrily orders the bouncers to go after him.

Menzies arrives nearby and calls the Doctor again, but unfortunately he says he’s lost Carmen in the traffic. She says they’ve identified the boat using CCTV and gives him directions so he can go straight to it. In the meantime, she takes another call from the officers accompanying Charley, who are watching the boat from across the bay. They’re about to give her a report when they’re suddenly attacked. Another voice comes over the phone and tells her to stay out of their business, but while the man is speaking to Menzies, Charley manages to get away.

Charley finds Carmen waiting by the quayside and, remembering what Lish told her earlier, she claims to be an old acquaintance who hasn’t seen her for about a year. Carmen is too embarrassed to admit that she can’t remember her, so she starts making casual small talk. Charley says she’s been meaning to get another trip on the boat for ages, so when the Captain arrives and invites Carmen aboard, it’s easy for Charley to persuade Carmen that they’re travelling together.

Fleeing from the bouncers, Lish runs straight into DI Menzies, who promptly handcuffs him and places him under arrest. Lish agrees to go quietly, but then they’re spotted by Brooks and his thugs. The men approach them and as Menzies reaches into her pocket to show them her warrant card, they knock both her and Lish out. Brooks orders his men to bring Lish aboard before he wakes up, but because he’s now handcuffed to Menzies, they have to bring her along too.

Aboard the High Straights, Brooks meets up with Carmen and tells her they’ll be heading for Rio in about twenty minutes. After everything that’s happened, he’s decided they ought to steer clear of Manchester for a while. She notices his bouncers are carrying two large sacks, but Brooks tells her they contain ice as the ice-maker in the bar is on the blink. After they’ve gone, Charley emerges from Carmen’s cabin (where she claims she was fixing her hair) and learns that their next destination is Rio. They hear the engines start to warm up…

Carmen tells Charley they’ve arrived in Rio de Janeiro and says she’ll like it if she sticks to the right parts. Charley is amazed, but then she’s even more impressed when she sees the huge casino inside the High Straights. This surprises Carmen as Charley had claimed to have been here before. Carmen says she lives aboard the ship and although she plays many of the games, her speciality is poker. She warns Charley that the biggest winner here is the House as it never loses, and the second biggest winners are people like herself - but for every winner there has to be a loser.

The Doctor races off to find the TARDIS, closely followed by the two police officers who are struggling to comprehend what happened to the boat as they saw it disappear before their very eyes. They’re happy to accept the Doctor’s explanation that it was just an illusion, but then two Tabbalac warriors materialise and demand to know where the ship went. The Doctor persuades them to let the policemen go, but the aliens tell him they’ve spent hours trying to break into his ship, but without success. Their leader receives a message telling him the other ship they’ve been tracking has been found. He orders the Doctor to take them aboard his TARDIS to that location and warns him that they’ll totally destroy this city if he refuses.

Menzies and Lish wake up and find themselves locked inside a room aboard The High Straights, which is where Lish he used to live. It’s a floating casino that hops instantaneously from planet to planet, but always at night so it’s always full of people. The clientele is exclusive and the owners are careful about who they invite aboard. The boat came to Salford after its owner, Brooks, heard about the super-casino that was planned for Manchester. He managed to get the project shut down. Lish says he used to be employed here as a cooler, someone who breaks people’s winning streaks. He explains that on his planet, the people can affect their immediate environment. Although they can focus their powers, they can’t stop it happening, and different people can affect things in different ways. He’s sometimes called ‘The Raincloud Man’ because his own particular “talent” is that he causes bad luck wherever he goes. He assures Menzies that Kelsa, and the other recent murders she’s been investigating, were simply the result of his bad luck - causing people to fall over and break their necks or crash into mirrors. He says he can’t control his condition and it’s been getting worse recently. He can shield one or two people at a time from his bad luck, but it’s taking more and more effort every time. There’s a device which dampens it, but whenever he leaves the ship people start getting hurt. Just then, one of the bouncers arrives and releases them from their handcuffs.

When the Doctor returns to the TARDIS he discovers the Tabbalac have covered it in a sentient sludge in an attempt to learn its properties. As they clean it away, they hear more aliens materialising. The Tabbalac warn the Doctor that the Cyrox are attacking, and before long a full-scale battle has begun. The Cyrox party is completely destroyed and the Doctor leads the Tabbalac inside the TARDIS before more reinforcements arrive. One of the Tabbalac has been killed, but their leader refuses to abandon the mission and says the cost is worth it if they can find the traitor.

Carmen shows Charley a separate room in the casino which she says is not for amateurs. This is the High Stakes Table where people can play any game they like as long as they’re willing to put up extremely high abstract stakes. Carmen explains that people gamble on things like their past, their future, their skills, their passion, their emotions and even on their life. People agree to these terms because either the House has something they desperately want or because they’re in so much debt to the House they don’t have any other choice. They watch as one of the players gambles with his youth - but he loses his bet and in an instant he’s transformed into an infirm, elderly man. Charley is horrified, but Carmen explains that she too made a high stakes gamble. It was nearly a year ago now, but she can’t remember what the deal was because part of the price is that she can no longer remember anything about her life before she came to live here. In fact, most of the residents live here after losing at that table and some of them were nearing the end of their lives and were playing to earn more time. Carmen says that although she can’t remember meeting Charley, she’s beginning to suspect they don’t really know each other. Charley admits the truth and says she just wanted to get aboard the ship.

Aboard the TARDIS, the Tabbalac leader becomes frustrated at the delay and says his people are used to travelling instantaneously, but the Doctor assures him it’s not a good idea to just go crashing in and out of reality. They eventually arrive at their destination - right in the middle of the casino. At first Charley is delighted, but then the Tabbalac leader storms across the room and demands that they hand over the “traitor” or else he‘ll start killing people. Carmen pulls Charley away and they try to sneak through a door behind them, but the Tabbalac automatically shuts and locks all the doors to prevent anyone leaving. The Doctor cheerily emerges and asks the Tabbalac how they’re getting on…

In his private office aboard the High Straights, Brooks is informed that the Cyrox Contingent has arrived. Although he’s clearly cautious, he does his best to greet them warmly. The Cyrox ask him if everything is ready and he assures them it is, but just as he proposes a toast, he’s informed by one of the bouncers that there’s some bad news…

In the cargo hold, the bouncer has just finished releasing Menzies and Lish when Brooks calls him back urgently, saying the ship is under attack. He orders the prisoners to stay where they are, then he races off to the casino room. Menzies is delighted and tells Lish the man forgot to lock the door behind him.

Brooks is becoming increasingly worried that the Tabbalac will start killing his guests any second. The Cyrox Contingent assure him he won’t have to wait long as the energy they need is already building, but Brooks pleads with them to hurry up.

In the casino room, the Tabbalac leader starts a short countdown - and then opens fire at the nearest guest, killing him instantly. The Doctor is furious and points out that they don’t even know for sure that the person they’re looking for is actually here. Charley wants to talk to the Doctor, but Carmen is wary of him and points out that he recently had her dragged down to the police station with some insane story that she’s a time traveller. Suddenly the Cyrox Contingent materialise in the room and order the Tabbalac to stop threatening the people. The Tabbalac refuse to stand down, so the Cyrox open fire. The room is soon filled with the sound of energy weapons and people screaming. The Doctor shouts to everyone to take cover and head for the nearest exit, but then he’s grabbed by one of the bouncers who accuses him of bringing the Tabbalac here. The Doctor assures him it was done under duress and not through choice, but the bouncer refuses to listen and tells him Brooks will want to have a word with him.

In the distraction, Carmen and Charley escape into a nearby corridor. Charley asks if she a secret stash of weapons on board, but Carmen says her plan was actually just to jump overboard and head for safety. Charley insists on staying behind in case the Doctor needs her.

The Cyrox leader informs Brooks that the battle is going well and reassures him that most of his guests have escaped. In fact, he says there shouldn’t be any need for further reinforcements. Brooks is relieved and asks them to capture the Tabbalac leader as he wants to talk to him. Moments later, the bouncer arrives, physically manhandling the Doctor who, by now, has realised all the bouncers are clones. Brooks demands to know who he is and why he’s brought the worst people in the Universe onto his boat. The Doctor thinks he’s exaggerating, but Brooks insists he knows what he’s talking about because he himself is a Tabbalac.

Menzies and Lish fight against the crowd who are trying to head in the opposite direction. Lish wants to go with them, but Menzies realises that if he leaves the ship he’ll end up causing accidents again. She refuses to let him do that to her city and is surprised when Lish tells her they’re no longer in Manchester, but in Rio de Janeiro. She drags him into a side room and asks him why he’s never tried to take the dampening device with him, but he says Brooks would be able to shut it down remotely. In any case, he used to be happy here - but now Brooks intends to hand him over to the Cyrox, the mortal enemy of Brooks’ own people. He says Brooks is a technical genius, but everything he makes is subsequently stolen by the Tabbalac government and used for killing, so about 200 years ago he built this boat and escaped to Earth. When he started visiting other inhabited worlds in the area he met Lish, who agreed to work for him at the casino, pretending to be a regular customer while influencing anyone who got too lucky. But now Brooks is selling him out and handing him over to the Cyrox who plan to take him to the Tabbalac homeworld where his powers would cause chaos. He doesn’t want to be responsible for destroying an entire race, even though it would stop the war and end all the suffering on Earth. Menzies suggests they find the Doctor, take the dampening equipment and get off the ship.

The Doctor tells Brooks he was forced to bring the Tabbalac here when they threatened to wreak havoc upon Manchester. Brooks accepts this and is pleased to see that the invaders have been quelled, albeit at a cost. The Doctor is curious about the Cyrox as they appear neither evolved nor designed. It‘s odd that he’s never heard of them either, despite the fact that he’s crossed paths with their mortal enemies the Tabbalac several times. Brooks explains that their neighbouring worlds ganged up on the Tabbalac and forced them to remain on their homeworld and live in peace. They’re only allowed to go offworld if their intentions are peaceful, but if they threaten to conquer anyone, they’ll instantly be confronted by the Cyrox. The Tabbalac were infected with a neurosis which created the Cyrox as a race equal and opposite to themselves. They’re a kind of hyper-intelligent virus which goes on creating more Cyrox as and when they’re needed. The outcome of any fighting is evenly balanced, but there are always more Cyrox than there are Tabbalac. Brooks doesn’t know who created the Cyrox or who provides the energy required to spontaneously generate their troops, but he knows it will never run out. The Doctor can’t understand why the Tabbalac keep fighting, but Brooks says they simply choose not to believe the threat.

Charley starts going through Carmen’s belongings in her cabin. Carmen can’t remember where she got any of the items from, but Charley finds a book that’s dated 2020 and a hairbrush with an in-built computer. This seems to prove that Carmen comes from the future after all. Carmen remembers finding the pound coin in her handbag and realises it must have been there before she played at the table and therefore she owned it before she lost her memory.

Lish takes Menzies to Brooks’ workshop and she’s amazed by all the junk he’s been storing. Lish confirms that Brooks keeps starting new projects, but rarely finishes them. They find the dampening generator and Menzies suggests they leave. They go out onto the deck, but then suddenly more Tabbalac reinforcements materialise and start ordering them to surrender the “traitor. Menzies and Lish don‘t know what they‘re talking about, so the Tabbalac start opening fire.

Brooks explains that he left his own people behind, but now they’ve come looking for him. The Doctor tells him he can’t stay here if his presence is going to endanger the people of Earth, but Brooks says he needs the revenue from his gambling business to fund his research. He says that before long he’ll have a plan that will sort out the Tabbalac for good, but before he can reveal what he has in mind, he receives another call from his bouncers alerting him to the arrival of more Tabbalac. Brooks decides to stay put, confident that the Cyrox will be able to take care of them, but the Doctor wonders what will be left of the city once they’re done…

Menzies recovers and finds that she and Lish are unhurt and have been enveloped in an unusual fog. The Cyrox leader explains that they’ve managed to contain the explosion and urges them to go back inside and take cover. Once they‘re inside, the explosion resumes as it should have done, and the part of the deck where they were standing is completely destroyed.

Brooks calls his engineer and tells him they need more power to be diverted to the defence shields. He tells the Doctor he’s lived with this stupid war all his life and he’s not convinced anyone can stop it, but the Doctor has other ideas. Brooks intends to remove the ship from danger, but the engineer tells him he’s having trouble charging the warp engines. Brooks is convinced the fuel supply has been sabotaged.

Although the Doctor is shocked by the mess throughout the ship, the Cyrox leader tells him this was a relatively clean battle. The Doctor thinks the war has gone on long enough but the Cyrox says it will never be over until the Tabbalac change their ways, which he thinks will never happen. The Doctor is impressed by the technology behind the Cyrox, but he’s not comfortable with the creation of a sentient species for the purpose of war, even if it’s a defensive one. The Doctor disapproves of the Cyrox plan to use Lish to throw the Tabbalac’s planet into total chaos, but the Cyrox leader tells him his people have no history of doing anything other than fighting this war and they have no culture of their own. Their only way out of this situation is to win, so the Doctor decides he’ll have to win on their behalf.

Menzies is reunited with Charley and gives her the good news that she’s no longer regarded as a murder suspect. Carmen confirms that the Doctor was right all along about her being from the future and explains that she used to be a time traveller but she lost her identity at the tables and has now forgotten everything. Charley asks if Carmen’s time machine is down in the ship’s vault and suggests using it to take them all back in time so they can nip all this in the bud before it even starts. Menzies doesn’t know much about time travel but she wonders whether they’re allowed to do that. Charley assures her she and the Doctor do it all the time and she thinks the Doctor will be grateful to them if they can sort the situation out. Menzies still isn’t sure, but Charley insists that she has the most experience of time travel. As they head off, Charley asks for reassurance from Menzies that she hasn’t mentioned anything to the Doctor about her own secret.

The Doctor is granted permission to speak to the Tabbalac leader, who’s been captured and locked up in one of the cabins. The Doctor tells him that despite all the dreadful things he’s done, he pities him. He says the Tabbalac are in a hell of their own making, but he still thinks they deserve a chance. He explains that the Cyrox are dedicated to eradicating the Tabbalac because that’s what they were created to do, but the Tabbalac leader thinks this is nothing more than propaganda.

Brooks is surprised when Lish and Menzies arrive at his office as he thought they were safely locked away. He admits that the first few bouncers he cloned were very intelligent, but now they seem to be suffering from diminishing returns and he really ought to think about refreshing their genetic mix. Charley and Carmen join them and demand he hand over the time machine, but Brooks points out that Carmen knew the rules when she played the game. When he learns that they plan to use the machine to resolve their problem he agrees, but says there’s an automatic protection in place to prevent people stealing the winnings and the only way they can get it back is if they actually win it during a gamble at the High Stakes Table. Lish says he can make sure Carmen wins it by tilting the luck in her favour, but Brooks says there are further defences against them winning against the House so she’ll have to play against another opponent. Brooks agrees to act as the punter and Menzies accompanies him down to the vault to collect the time machine and Carmen‘s memories, but as they’re about the leave they hear a huge crash and they realise the shields have failed. A huge hole appears in the side of the vault and the Tabbalac reinforcements start climbing in. Brooks and Menzies race outside and seal the door behind them.

In the casino, Charley secretly asks Lish if it’s possible for the table to ’gift’ the winnings to a third party. When he says it is, she asks him if he can give the time machine to her as she’s not sure they can rely on Carmen. Once she gets her memory back she might be an entirely different person and might not be willing to help them. Brooks arrives with the two tins from the vault and Lish says they’re going to be playing roulette with a 50-50 chance of winning on either red or black.

Hearing the noise outside, it’s obvious to the Doctor that the Tabbalac reinforcements have arrived, but this means there‘ll soon be more Cyrox too. The war will soon be spilling out into a city full of innocent bystanders. Menzies arrives with the news that the Tabbalac are breaking in, but although they’ve taken over the main hall where the TARDIS landed, the High Stakes room is still safe. As the Doctor leaves, he asks the Tabbalac leader to think about what he said, but all this does is make the creature laugh. Once they’re alone, Menzies tells the Doctor that Charley’s plan is to restore Carmen’s memory and time machine so she can go back in time and stop all this from happening. The Doctor is horrified and Menzies realises she was right to be concerned. When he hears that Charley is claiming they both change the course of history all the time, he decides it’s time he had serious words with her.

At the High Stakes table, the croupier sets the roulette wheel spinning...

Worried that they may be too late, Menzies decides to retrieve the dampening device that Lish dropped on the deck earlier. She tells the Doctor it prevents Lish - the Raincloud Man - from causing the punters to have bad luck, so if they can switch it off, his bad luck should start to affect Carmen and the stakes will revert back to the House. The Doctor deactivates the device.

The roulette wheel comes to a stop - but to everyone’s surprise the ball lands on green, which means there are no winning bets and therefore the House wins. Charley accuses Lish of messing things up, but the Doctor arrives with Menzies and explains that the situation was taken out of his hands when he switched off the dampener. He switches it back on and tells Charley her plan was insanely irresponsible. She tries to convince him it sounded like a good idea at the time, but he says he has a three-hour lecture ready for her later which will explain why it wasn’t. The Doctor examines the technology that operates the gaming table and can’t believe how powerful it is. If the Tabbalac think Brooks was prepared to share it with the Cyrox, it’s no wonder they’re so keen to track him down. Reluctantly the Doctor has to confess that Charley’s “dreadful” idea has given him a good one.

The Doctor returns to the Tabbalac leader and makes him an offer. He says he wants to put a stop to the war once and for all and suggests they put the war up as a stake on the ship’s High Stakes Table so they can gamble for it. The leader asks what the Doctor is prepared to bet in exchange and he offers to put up the TARDIS and his knowledge of how to operate it. He knows the Tabbalac can tell when anyone is lying, so he asks the leader to assess whether or not he’s bluffing. The Doctor tells him to order his troops to cease hostilities and the Cyrox will then do the same. The Tabbalac leader reluctantly agrees, then he invites the Doctor to name his game…

At the table, the Tabbalac leader insists that only he, the Doctor and the dealer be allowed to stay. Reluctantly, the rest of the group are forced to leave the room, but Lish stays behind to act as dealer. The Doctor produces a pack of Top Trumps cards and explains that each card has a series of categories and values, and each player picks one where they feel their card excels. They have a trial run and the Doctor shows how it’s possible for players to win cards off their opponent and add them to their deck until the other player runs out of cards. The Doctor invites the Tabbalac to shuffle the cards, then Lish deals them out. He offers the Tabbalac the chance to go first, but the Doctor wins as his card shows a higher engine capacity…

The others are waiting impatiently outside. Brooks reports that the Doctor has won the first three games, but he knows the Tabbalac will play till the last card as they never like to turn down a bet. Menzies has been watching the Tabbalac and Cyrox armies staring each other out, but Brooks is more worried about the damage already caused to the marina. It looks like this is yet another place he’s going to have to steer clear of for a while. Menzies wondered what happened to the local police, but Brooks says his people have very effective ways of immobilising them. At least if the Doctor wins there’ll be a city left for them to explain it to…

The Doctor continues winning, but the Tabbalac is starting to get the hang of the game. The Doctor tries to persuade him to quit while he can, but the alien insists on playing one final round even though it means the war will end if he loses. The Doctor agrees that the next card will be the decider, so everything hinges on who wins. Before they play, the Tabbalac says there’s just one more thing he wants to do - then he raises his weapon and shoots Lish dead. The Doctor is horrified, but the Tabbalac leader says Lish was putting him off his game. He insists the Doctor take over as dealer. Hearing the commotion, Brooks retrieves a master key and bursts into the room with Menzies, Charley and Carmen. The game continues and this time the Tabbalac is successful and the Doctor has to hand over his losing card. The Tabbalac is delighted and says he knew they were trying to cheat him by using their cooler.

It looks like they have nothing left to play with, but the table detects something that could be worth a great deal to the Tabbalac. Brooks points to a flashing readout on the table and then, to the Doctor’s surprise, the Tabbalac agrees to play the whole round again. Everything is on the table - the TARDIS and the knowledge to pilot it as well as the outcome of the war - in return for access to Charley’s memories of her travels with the Doctor. The Doctor can’t understand why they should be so valuable, but the Tabbalac is under no obligation to explain his reasons. Charley asks what they’ll do with her memories, but the Doctor doesn’t know and says it has to be her decision. She knows she doesn’t really have any choice and reluctantly she agrees to take over the Doctor’s position at the table and declares that if she wins, the stakes will go to him.

The game begins and the Tabbalac chooses the category on his first card. Then, one by one, they move through the entire pack. Sometimes Charley wins a card, and sometimes the Tabbalac wins, but eventually Charley starts to get the upper hand. At the end of the game, she’s announced the winner and she leaps up and down with joy - but the Tabbalac leader refuses to accept it and orders his warriors to resume hostilities. The Doctor points out that there are no forces outside the room any more. The table is so powerful it can actually twist reality and because the Tabbalac leader lost the game, his race has automatically lost the war and all his troops are now being held prisoner on the Cyrox homeworld. The leader becomes furious and raises his weapon, ready to kill everyone in the room, but Brooks orders him to show proper dignity and follow the rules. The Tabbalac accuses him of being a traitor, but Brooks says everything he’s done was to help save his people and stop the war. He tells the leader to open his eyes and see the truth, but the Tabbalac refuses to listen and opens fire. Brooks falls to the ground and with his dying breath he tells the others that he did his best, but in the end the odds just weren’t in his favour.

The Doctor asks the Tabbalac leader if he’s proud of himself, but before he can reply the cavalry arrives in the form of the Cyrox leader and his troops. The Cyrox tells his opposite number he’s the last undefeated member of his army and it doesn’t make sense for him to continue fighting. Again, the Tabbalac leader refuses to listen to reason and starts shooting, so the Cyrox return fire and the leader is shot down. Just before he dies, the Tabbalac tells the Doctor that at the very last minute he was able to read Charley and he sensed how she knew for certain that the Doctor wouldn’t lose the TARDIS. The Doctor asks him to explain what he means by this, but it’s too late.

The Cyrox prepare to leave and the Doctor tells them he thinks they’ve earned the right to be set free of the war. Once they’ve gone, the survivors notice a terrible noise and the Doctor warns everyone the boat is sinking due to the damage sustained in battle. Carmen points out that the High Stakes Table is a very valuable piece of equipment, but the Doctor thinks it would be better if it went down with the rest of the ship. Charley does a quick check to make sure there isn’t anyone else on board, then they all get to the harbour where it should be safe. The Doctor orders everyone to stand well back, then he strikes a match and ignites a trail of alcohol that leads back to the High Straights. Seconds later, the entire ship explodes in a ball of flame.

Menzies wonders whether the marina has insurance against the damage caused here today. The Doctor assures her things could have been a lot worse, but fortunately the two alien armies were concentrating mainly on each other. Carmen reveals that she managed to get away with quite a lot of cash before they left the ship and she offers to donate it to any victims. The Doctor is surprised she didn’t create more of a fuss when he said he was going to destroy the High Stakes Table, but she’s decided she’s quite ambivalent about getting her old memories back. After all, who knows what she was like before? She could have been anybody and come from anywhere. The Doctor judges from her time machine that she’s a human and probably comes from the 108th or 109th century, but Carmen doesn’t mind and is perfectly happy being a clean slate. She tells them this is as good a place as anywhere to settle down, so she says goodbye to her new friends and heads off for her new life.

Menzies asks the Doctor if she can travel with him and Charley in the TARDIS and he says he gets asked that question about four times every year. She tells him her life back in Manchester has got a bit complicated, but he warns her his life is complicated too. In the end, he turns down her request. He says there’s something very odd about Charley that just doesn’t add up, so the timing isn’t right for Menzies to come along. They both agree that maybe one day it might be possible. Menzies understands and advises him to keep a close eye on Charley, but he says he already has every intention of doing just that.