Although the regeneration may have started, this time it will not be so straightforward. Seemingly unchanged by the process, the Doctor stretches his arms out towards the jar containing his severed hand and siphons the regenerative energy into it. As his companions look on, somewhat bemused, he leaps back into action.
Outside, Sarah cowers in fear of the two Daleks about to exterminate her, but is saved moments later when Jackie Tyler and Mickey Smith appear, both brandishing weapons similar to the one carried by Rose. They destroy the two Daleks and Sarah clambers out of her car, as Jackie demands to know where Rose is.
In the Torchwood Hub, a Dalek advances through the entrance portal as Gwen and Ianto open fire. Although their bullets have no effect, they are stunned when the Dalek stops moving. Lowering their weapons they step forward and discover the bullets are suspended in midair, as if some force field is shielding them and freezing everything outside.
Back in the TARDIS, the Doctor examines his severed hand, which is now glowing with golden light. He explains to his three friends that he used some of the regenerative energy to heal the damage done by the Dalek but halted the process before he could be completely changed – therefore he is the same Doctor. When he is through explaining Rose steps forward and the two embrace. Donna suggests she and Jack do the same, but he is not so sure.
In the Hub, Ianto uses the computer to discover that the force field is a Time Lock, implemented by Tosh before she was killed. Torchwood is now suspended in a bubble, nothing can get in but they cannot get out without unlocking the Dalek sitting nearby. Jack is their only hope.
In London, the Daleks manage to locate the TARDIS and the Supreme Dalek orders for it to be brought to the Crucible. Inside the ship all of the lights go out and the Doctor realises they are trapped. As Sarah, Jackie and Mickey arrive outside to watch the proceedings they see the TARDIS disappear. Sarah realises they too must go to the Dalek Space Station, and with the trans-dimensional teleports used by Jackie and Mickey out of power for the next thirty minutes, she offers herself to the Daleks in order to be taken away. After a few moments Jackie and Mickey disarm themselves and follow suit.
Elsewhere in London, Martha prepares to activate Project Indigo again, claiming it is time she used the Osterhagen Key as instructed by General Sanchez. Despite her mother’s objections she teleports away, and arrives in Germany, sixty miles from Nuremberg. Getting to her feet she looks around – the area is swarmed with Daleks.
As the TARDIS is dragged toward the Crucible – the massive structure at the centre of the web of stolen planets – the Doctor turns to Rose, recalling that her parallel universe is running ahead of his own. He asks what happened in her world and she explains that the sky above the Earth was being claimed by darkness – the stars were going out one by one. She then tells him that her version of Torchwood managed to build a Dimension Cannon, which allowed her to cross dimensions in search of the Doctor. She discovered that the walls of reality were beginning to crumble – even the Void between dimensions has been decimated, something has been tampering with reality.
Recalling her previous encounter with Rose, Donna asks why she seemed so adamant that she was special in some way, and Rose tells her that when her Torchwood used the Dimension Cannon to measure different timelines, they all seemed to converge on her, which Donna finds unlikely, as she sees nothing special about herself.
Eventually the ship arrives and the Supreme Dalek orders the Doctor to step outside. Rose and Jack protest but the Doctor claims they cannot fight back – when they faced the Daleks before the creatures were half-breeds, now they are up against a full-blooded Dalek Empire, even the TARDIS will not withstand attack. As the three companions continue to talk about the situation, Donna stands alone, a strange rhythmic heartbeat sounding inside her head.
Preparing to face the terror outside, the Doctor turns to each of his three companions in succession and tells them they were brilliant, and together they step outside, all bar Donna, who seems overcome by the beating in her head. Suddenly the TARDIS doors close and she is stuck inside. The Doctor tells the Supreme Dalek to let Donna go but it claims not to know what is happening. Labelling the TARDIS as a weapon it orders for it to be destroyed, and the vessel is dropped through a trap door into the depths of the Crucible, with Donna still inside.
The Supreme Dalek explains that the TARDIS is going to be plunged into the core of the Dalek Ship, which will burn it to dust. Sure enough the ship is flung into the burning heart of the Dalek Base and Donna is left helpless as the roundels on the walls begin to shatter and flames start to billow from the heart of the ship. The Doctor, Jack and Rose are made to watch as the Time Lord ship starts to crumble. Inside, Donna is flung to the floor, and once again she hears a heartbeat, which appears to be coming from the Doctor’s severed hand. She reaches out to it and as golden light swirls around her, the glass case breaks. Recovering from the ordeal, Donna watches as the hand starts to grow. The golden light spreads across the floor and in a matter of seconds the body of the Doctor is lying on the floor, naked.
On the bridge of the Crucible, the three travellers watch as the TARDIS disappears amidst the burning core, and the Doctor is left defenceless. Outraged, Jack takes out a pistol and fires at the Supreme Dalek. The bullets have no marked effect and he is shot down. Unbeknownst to the Daleks and Rose, however, Jack is not dead. As the two remaining prisoners are led away to see Davros, the Doctor catches the very-much-alive Jack winking at him.
Despite it’s ordeal in the heart of the Crucible, the TARDIS has not been destroyed. With the New Doctor now dressed in a blue suit (as opposed to the brown one worn by his counterpart), and the damage to the ship repaired, he tells Donna not to make a sound or else the Daleks will be able to detect them. Donna, however, is more concerned about the cloned Doctor she saw grow from the hand in the jar. He explains that he was born from the regenerative energy unused by the Original Doctor, sparked into existence with the help of Donna. He is the first of a new species – a Time Lord-Human metacrisis. As he talks he begins to notice a significant change in his biology – he has only one heart.
Donna recalls the heartbeat she heard and the Doctor explains it is his own, echoing back in time and converging on Donna. Again Donna questions why she is at the centre of things and once again the Doctor tells her it is because she is special, a claim she still refutes. Apparently understanding the workings of Donna’s mind since the metacrisis, the Doctor begins to realise that Donna really does believe she is useless.
Suddenly things begin to clear in his head and he become conscious that there is more than sheer coincidence in the two of them being together. First she was brought to the TARDIS, then he met Wilf, then she found him again – and not only that, the day they found each other again it just so happened her car was parked metres away from where the TARDIS was due to land. Even now it seems the ties that bind them are not yet fully woven – they are heading towards the end of something…
Back on Earth, Martha makes her way through the woodland to a castle, where an elderly housekeeper greets her. She takes her inside and Martha prepares to set about her work. She enters one of the many rooms and approaches a bookcase. Upon uncovering a hidden computer panel she opens up the door to a lift, which will lead her to what she needs. However, the housekeeper has heard of the Osterhagen Key and what it will do when activated. She pulls a gun on Martha and threatens to shoot, but eventually Martha convinces her that she must be allowed to do as she was instructed and use the key. The housekeeper lowers her pistol and Martha steps inside the lift.
Onboard the Crucible, Jack is thrown into the incinerator, but manages to escape and runs off further into the ship. In Germany, Martha emerges in a small control chamber and sends out a message to any other members of UNIT who will be able to help activate the key.
Soon Sarah, Mickey and Jackie are all escorted onto the Crucible, along with a crowd of other prisoners. Down below in the Vault, Rose and the Doctor are held in two apparently invisible security cells. The Time Lord demands to know what is going on and questions why Davros has been left in the lower levels of the ship. He realises that his old enemy is still not in complete control of his Daleks; he is being kept as a pet.
Davros rises above the Doctor’s jibes and introduces his two prisoners to the remains of Dalek Caan, whom he says foresaw the two companions being together at this moment. Having flown unprotected into the Time War, Caan saw all of time itself and knows what is to happen soon – the end of everything is approaching, and one of the Doctor’s Children of Time will die. The Time Lord grows angry; demanding to know whom it was that locked Donna in the TARDIS. Davros takes delight in the mounting emotion, and again he turns to one of Caan’s prophecies – which declare that soon the Doctor’s true soul will be exposed. Davros claims that he and the Doctor will witness one final journey together, and tells him he has arrived in time to witness the testing of his new experiment – the Reality Bomb.
The crowd of prisoners are brought to a halt in a large chamber onboard the Crucible. When one of the group collapses and the Daleks are distracted, Sarah and Mickey take the chance to escape. They run and seal themselves away in another chamber and look on as Jackie, who has stopped to help the fallen woman, looks up to the ceiling far above, where a massive armament has been constructed. As the Supreme Dalek counts down to the testing of the device, alias Davros’ bomb, the Doctor begins to realise what the stolen planets are for. The formation of the planets creates a massive amount of energy, which the Reality Bomb concentrates it into a singularity – giving it enough power to destroy matter entirely. Onboard the TARDIS the Duplicate Doctor and Donna inspect scans of the Crucible and discover the same thing.
Back in the prisoner’s chamber, Jackie and the others look on as the device above their heads begins to glow. Mickey then realises that the teleporters he and Jackie are carrying have now recharged. He motions for his friend to activate the device and she beams away to safety, standing with Sarah and Mickey as the Reality Bomb is fired upon the other prisoners, reducing them to clouds of atoms.
Down in the Vault, Davros explains that the Reality Bomb cancels out the electrical bond between every atom, causing them to disperse. With the power of the twenty-seven stolen planets at his dispersal, his invention will be able to transmit a wave big enough to destroy any living thing in any universe or dimension – as Rose has already witnessed, the stars are about to go out.
As the Daleks prepare to unleash their cataclysm, the Supreme Dalek recalls all other Daleks to the Crucible to seek shelter. Leaving the planet behind, the people of Earth begin to think their worries are over, but as Wilf predicts correctly as he and Sylvia walk the deserted streets of London, the ordeal is not finished yet.
Still hidden from the Daleks, Mickey, Jackie and Sarah are shocked to discover Jack crawling around in the service shafts. After he and Mickey greet each other, Sarah declares that she has something to fight the Daleks with. She produces from her jacket a necklace, on which is hung a shining gem, which Jack identifies as a warp star. It was given to Sarah by a Verran Soothsayer, for use at “the end of days”. Jack explains that a warp star is essentially a giant explosion waiting to happen.
Back on Earth, Martha makes contact with two other UNIT officers, who together prepare to activate the Osterhagen key. However, Martha is not prepared to destroy the Daleks yet without first taking a leaf out of the Doctor’s book.
Inside the TARDIS, the Duplicate Doctor and Donna begin constructing a weapon to fight the Dalek forces with. Knowing that Davros’ genetic code runs throughout the entire race of Daleks, the Doctor intends to lock the Crucible’s transmission onto the evil genius, thereby wiping out the Daleks in a massive backfire.
On the bridge of the Crucible, the Daleks receive an incoming transmission – it is Martha. The link is sent down to the Vault and the Doctor makes contact. At last Martha explains what the Osterhagen Key is – a chain of warheads placed beneath the Earth’s crust – the final option if the human race’s suffering becomes too great to reverse. Realising the Daleks need all twenty-seven planets for something, Martha threatens to deprive them of one of them, thereby thwarting their plan and saving the people of Earth from an even worse fate.
Moments later a second transmission is received, this time from inside the Crucible itself. It is Sarah, Jack, Jackie and Mickey, who are threatening to use the warp star in order to destroy the Crucible. As Davros marvels at seeing Sarah again, so long after their first encounter on Skaro, Rose turns to the Doctor to find him looking far from happy. Dalek Caan claims the Time Lord’s soul is at last revealed, and Davros begins to goad his old enemy by claiming that despite his entire crusade for what is right and good, the man who abhors violence manages to take ordinary people and turn them into weapons and murderers. After revealing the fate of Harriet Jones, Davros questions how many people have died in the Doctor’s name; and the Time Lord cannot deny that the number is vast indeed. At last Davros succeeds in exposing the Doctor for who he truly is – the man who runs and does not look back for fear of shame.
The Supreme Dalek then orders for the Doctor’s companions to be brought to the Vault, and sure enough, before they can act on their threats, Martha, Sarah, Jack, Jackie and Mickey are all brought before Davros. He orders them to kneel and forces them to watch, as the Reality Bomb is primed for universal detonation. The Doctor pleads with him to stop but it is too late, maddened by his approaching victory, Davros begins giggling and laughing manically.
Just as all seems lost, Donna and the New-born Doctor appear in the TARDIS. The half Time-Lord, half Human runs forward with his weapon, but Davros is one step ahead. Firing a bolt of electricity from his robotic hand, he throws the Doctor to the floor and places him in a holding cell. Donna runs forward and grabs the fallen gun but she too is blasted back, falling against a nearby control panel. The gun is destroyed and Davros blasts such resistance as pathetic.
The final countdown begins and the Doctors and their companions look on. As Donna gets to her feet, somewhat dazed by her fall, the Reality Bomb prepares to fire, but it is stopped when suddenly the system shuts down. All eyes turn to Donna, who has used the control panel to shut down the device, much to the bemusement of the Doctors. Not finished yet, she then proceeds to disarm Davros’ robotic hand, cancel out the Dalek’s weaponry and close down the holding cells trapping the Doctors and Rose. Astonished by her newfound intelligence, the Original Doctor asks how this has happened and Donna explains that the metacrisis that created the new Doctor was two-way. As well as placing some human attributes in the new doctor, it placed some Time Lord attributes in her. With the intellect of a Time Lord and the instinct of a Human, she is capable of more remarkable feats than even the two Doctor’s can achieve. Working together the three of them begin disabling the Daleks all over the Crucible, whilst the other companions set about clearing the Vault.
With the Crucible disarmed, the Daleks malfunctioning and Davros held at gunpoint by Mickey, the Doctors and Donna begin sending all of the stolen planets home using a device called the Magnetron. Rose asks what has happened to Donna and she explains about the metacrisis, and how the new Time Lord genes inside her were only activated following the shock of electricity administered by Davros. Now, with effectively three Doctors at work, they can undo all of the Daleks have done and restore normality. The timelines that converged on Donna were waiting for this moment in time, when she would become the person who had the power to save the whole of reality.
Turning on Dalek Caan, Davros asks why he did not foresee this happening. However, Caan has not lied. He foresaw the end of everything, but it was not the end of reality, it was the end of everything Dalek. Seeing all of time, he understood the pain and suffering his race brought and he determined to stop them, buy ensuring the timeline that brought the Doctor and Donna to the Crucible was not altered, he could ensure she was in a position to stop Davros – it was therefore Caan who closed the TARDIS doors in order to make sure Donna was present to initialise the metacrisis.
Descending into the Vault, the Dalek Supreme opens fire and zaps the control panel, but is stopped from causing any further harm by Jack, who blasts it with his gun. The Doctors discover that the Magnetron has been wrecked and only one planet is left – the Earth – now they will have to use the TARDIS to take it home. Whilst the Original Doctor readies the ship, his counterpart continues work in the Vault, listening as Dalek Caan tells him to destroy the Crucible and end the reign of the Daleks completely. This he does, and uses what is left of the control panel to overload the Dalek’s power feeds, causing them all to blow up, including the one in the Torchwood Hub, which in being destroyed manages to break the Time Lock.
Angered by his counterpart’s actions, the Original Doctor ushers everyone back into the TARDIS as the Crucible begins to overload. Showers of sparks begin to fall and flames engulf large parts of the Vault. Seeing Davros and Dalek Caan sat alone across the chamber, the Doctor offers his nemesis safety, but he will not take it. As the station crumbles around him, Davros names the Doctor as the destroyer of worlds. He gargles in pain as the flames lick higher, and Dalek Caan is left to assert his last unfulfilled prophecy – one of the companions will still die.
As the TARDIS takes off, the Original Doctor contacts Torchwood and tells them to open up their Rift Manipulator device and allow all the energy to be picked up by the TARDIS. He then contacts Luke and Mr Smith and asks them to seal the link between the TARDIS and the Torchwood Hub. However, Mr Smith requires the TARDIS base-code numerals in order to do this, and registering that will take a long time. However, Sarah has a trick up her sleeve. Speaking into the scanner she calls for K-9, who appears in the attic and links up to Mr Smith, feeding him the data he needs.
Soon the connection is ready and the TARDIS is all set to tow the Earth home. However, this time the Doctor is not going to be piloting the ship alone. Positioning Rose, Martha, Jack, Mickey and Sarah at each of the console panels (he asks Jackie not to touch anything), and with he, his clone and Donna ready to assist when required, he explains that the ship is actually meant to be piloted by six people, but he has to make do on his own – hence his somewhat chaotic piloting style.
With everyone in place the ship is set in motion, slowly but surely pulling the Earth along through space. On the planet itself, Gwen, Ianto and Luke all whoop with joy, whilst the Doctor’s Children of Time work together at the ship’s controls to take the Earth back home – united at last. Eventually the Earth is returned safely, and celebration floods across the planet. Wilf and Sylvia dance for joy as light is returned and Francine Jones walks out into the open air to look again upon the familiar sky.
Landing the TARDIS in a park in London, the Doctor (in his original form) begins to say goodbye to his companions. Before rushing off home to see Luke again, Sarah chides her old friend for acting like such a lonely man, when in fact he has a far bigger family than many people on Earth. As she departs, Jack and Martha step outside; ready to return to their lives on Earth. After disabling Jack’s teleport and telling Martha to get rid of the Osterhagen Key system, he bids them farewell.
Next Mickey steps outside, having decided he no longer wishes to live in a parallel world, where there is nothing for him now that Rose is no longer his girlfriend and his grandmother has passed away. He thanks the Doctor for everything then walks off, joining Martha and Jack as they leave the park.
Finally, he decides to send Rose and Jackie home too, to the parallel world where they have now made lives for themselves. He pilots the ship to Norway, on the beach where he and Rose last said goodbye. Donna explains that soon the walls between realities will be closed for good, and Rose suddenly becomes desperate to stay with the Doctor. However, he insists that she now has a job to do – look after his clone. Born in battle and responsible for genocide, the Duplicate Doctor needs to be kept safe and stopped from doing wrong again. Just as Rose managed to save the real Doctor when they first met, she must do the same for his copy. However, with only one heart and no possibility of regeneration, this new Doctor will grow old and die with Rose – at last she can be with him forever.
Despite this, Rose is not convinced that the new Doctor is the man she fell in love with, and to test that she asks him to recall the words he meant to say to her the last time they met, he began by saying “Rose Tyler…” but was cut off from speaking. The Original Doctor claims the words he meant do not need to be said, but the Duplicate Doctor whispers them in Rose’s ear. They kiss passionately and the Original Doctor and Donna leave, returning to their own reality.
Inside the TARDIS, Donna theorises where she and the Doctor might go next. However, the Doctor knows that something is wrong. He looks on as Donna begins to get tongue-tied trying to recall people and places. Eventually it becomes too much for her and she leans forward, evidently in pain. The Doctor stands before her and asks if she knows what is happening. She claims she does. They both know that a Human-Time Lord metacrisis cannot exist because it is impossible to sustain. Knowing she may be moments from death, Donna laments that she wished to spend the rest of her life with the Doctor. Travelling together throughout the cosmos, they could have seen and done so much more, but now all of that is doomed never to happen.
However, the Doctor will not let Donna die, he has another plan. Donna begins to realise this and begs him not to send her back home. Despite her pleas, he hugs her tightly and tells her they had the best of times together. He apologises to her then clasps his hands to her head. With a horrifying gasp Donna’s body goes limp, and the Doctor is left holding her in his arms.
One stormy night on Earth the Doctor returns her home, where Wilf is waiting. They lay her to rest on her bed and then return downstairs to Sylvia. The Doctor at last explains what has happened – absorbing the Doctor’s mind was too much for Donna to cope with and it was beginning to kill her. To save her life he wiped her mind completely of all traces of the adventures they spent together – she is now returned to the woman she was before she met the Doctor – the Donna Noble he knew, the woman he helped her become, is dead.
He warns Wilf and Sylvia that they must never remind her of the time she spent with him, because the second she remembers she will die. Wilf protests, claiming (despite Sylvia’s remarks to the contrary) that Donna was better with the Doctor, and the Time Lord replies by telling them that there are worlds in the universe that exist in peace and happiness because of Donna, and for one moment she was the most important woman in the universe. Sylvia claims that she still is as she is her daughter, and the Doctor snaps by telling her to say that to Donna once in a while, if for nothing more than to make her feel valued.
Suddenly Donna enters, oblivious to what has gone on, assuming, as the Doctor predicted, that she has missed the ball and does not recall the extraordinary events that have just occurred. She says a half-hearted hello to the Doctor then goes to kitchen to phone her friends and chat banally. Sylvia then asks the Doctor to leave, and after one more goodbye to the woman he lived through so much with, he departs.
On the doorstep, Wilf watches the Doctor return to the TARDIS, but before he goes he promises to look up to the sky each night and think of him on Donna’s behalf, grateful for the wonderful things he showed her. As the Time Lord goes on his way, Wilf stands to attention and salutes him, and then returns indoors. Inside the TARDIS, the Doctor tends to the console. With all of his friends somewhere else with other people to care for, he walks quietly around the ship, alone once more…