The plane carrying Sarah and Josh leaves McMurdo in Australia on course for the Nikita Base in Antarctica. Will Sullivan tells them they have good landing conditions at the moment, but the weather is deteriorating rapidly. He’s surprised to learn of the two passengers, but as the flight is still two hours away, it’ll give him time to lay out the red carpet. The pilot, Jack, assures Sarah that landing shouldn’t be a problem, but taking off again later may be a bit tricky. He knows her from her earlier TV appearances for Planet 3 and regards her as a celebrity. Jack tells them there are rumours that the Russians once found something unusual in the area but details were never made public. When the Antarctic Treaty was ratified, the ice was protected from exploitation, so the Russians pulled out and Munro decided to take over their old base. He warns her that most of the other research teams have already left for the Winter and the place is almost deserted, but Sarah had no choice as she was forced to delay her plans to visit earlier. There are now only three scientists left at Nikita - Munro, Will and Morgane Kaditch, a French scientist who’s rumoured to be a real heart-breaker. Josh is suddenly interested…
Two hours later, the plane is cleared for landing. Will tells Morgane that their visitors should be with them shortly and she’s worried that Munro is paranoid enough already without strangers arriving. Will knows this only too well and he would never have invited them if he’d known what the situation was going to be like. Dr Gideon Munro overhears them and accuses them of talking about him behind his back. Will tells Munro that he’s noticed he’s been under a lot of strain recently, but Munro insists he’s still in charge of the project and he refuses to be patronised. He believes his colleagues have been trying to undermine him and he now regrets agreeing to Will’s request for Sarah to visit. It’s too late to stop them now, but he hopes they’ll be satisfied with a quick tour and will leave before the weather closes in. As Munro leaves to greet the new arrivals, Morgane urges Will to do something before it’s too late…
The plane finally touches down and Dr Munro and the others go out to greet their visitors. Munro thanks Sarah for the generous donation and adds that without private sponsorship the project would be virtually impossible. As they head back inside, Sarah is surprised to learn from Will that he’d been trying to send her messages over the last week, but he doesn’t explain what they were about. Morgane welcomes Josh and promises to make his first trip to Antarctica one to remember. She tells him she only has three days left before she’s due to leave herself. Jack stays behind to check a warning light flashing inside the plane, but will join them later.
Munro completes the guided tour, covering the common room and kitchen and the sleeping areas. Will explains that the base has larger storage areas, but they’re not heated so all the activity is centred around one small building. Morgane is due to go to the drilling site later and invites their guests to join her. She gives them both a panic button which will transmit a homing signal to the others if they get lost on the ice. Although Josh agrees to go to the drill site, Sarah is more interested in finding out about the outcome of their research than the actual process. She asks Munro if she can see any preliminary results and he leaves to prepare a report.
Once they’re alone, Will tells Sarah he wishes she hadn’t come as there’s a massive storm front moving in and there’s a chance they may get stuck there. Sarah realises he’s scared of something and asks him how he got his black eye. He claims to have walked into a door, but that doesn’t fool her for a second and he reluctantly admits that Munro punched him a few days ago after accusing him and Morgane of plotting against him. He’s believes Munro is cracking up and is getting increasingly paranoid. This sort of behaviour has happened before on the Antarctic and he recounts an incident ten years ago when the FBI were called in after two Americans tried to kill each other, and another incident in the winter of 1983 when an Argentinean torched his own base, forcing everyone to be evacuated. When things go wrong here, they usually have fatal consequences. As base physician, Will is able to offer medication to Munro, but he can’t force him to take it. Jack returns and tells them the problem on the plane was worse than he thought and it’s unlikely they’ll be able to leave today. He asks to borrow some tools and Will directs him to the main storage hut. Sarah decides it would be a good idea for her to talk to Munro alone so Will decides to accompany Morgane and Josh to the drilling site.
Sarah catches up with Munro and explains that they’ll probably have to stay the night after all. He says that won’t be a problem as they have plenty of space now the summer team have departed. He pours her a whisky and she asks him about his background. He tells her his father and grandfather were church ministers and he’s regarded as the black sheep of the family. Sarah reveals that she coaxed details from Will about how he got his black eye and Munro says he regrets his actions. He believes Morgane is the real trouble maker and compares her to the Sirens of Greek mythology. He warns Sarah that Josh should keep his distance from her and implies that Morgane and Will are sharing a bed. Sarah becomes uncomfortable with the way the conversation is developing and makes an excuse to leave. He advises her to wear goggles if she’s planning to go outside as the ambient light in Antarctica can cause snow blindness.
Will and Morgane bring their Snowcats to a halt and Josh gets out, amazed at the spectacular mountainous landscape. They’ve arrived at the drilling site, but it’s a bit dull and consists of just a few holes in the ground. But Morgane believes that what’ve found beneath the ice could change the world! Josh knows they’re investigating climate change, but Dr Munro has forbidden them to discuss any of the details until they’re ready for publication. Suddenly Morgane has a dizzy spell and nearly passes out. Will believes she’s suffering from exposure as she’s been coming out to the site a lot recently, but she says she’ll be fine in a moment. She agrees to return to the base alone, leaving Will to show the nearby penguin colony to an excited Josh.
Sarah checks on Jack, who’s just finished checking the plane. He’s found the problem, but fixing it will not be so easy. He asks her to sit in the cockpit and switch things on and off while he examines the engine. He guides her through what he needs and she reads off some of the instrument panels for him. They see Morgane returning on her Snowcat and Jack tells Sarah that he’s heard rumours that Will and Munro were both smitten by her and have been fighting over her affections.
Will and Josh trudge across the icy landscape, but they soon start to fall out and argue over their concern for Sarah and Josh’s flirting with Morgane. Will warns him to be careful of Morgane, but Josh realises it’s his relationship with Sarah that’s really bothering him. Josh accuses him of being jealous, but Will says he’s out of his depth and should go home. When they reach the penguin colony, Will is shocked to discover the birds have all gone. He suddenly notices the mountains on the horizon have disappeared under the approaching storm. He estimates they have less than ten minutes to get back to the Snowcat or they’ll be trapped…
Sarah uses the base’s radio to call Will and Josh, and they respond with a warning that the storm front is closing in fast and they’re on their way back. She tells them that somebody has left a note on her bunk telling her to meet them in the main storage hut. She doesn’t know what it’s about, but she has a suspicion that it might have something to do with her first visit to Antarctica in which something dangerous was found in the ice. Will advises her to wait until they’ve got back, but she’s confident she can look after herself. Josh urges Will to go faster…
Sarah enters the storage hut and calls out to see if anyone is there. As she looks around, the door opens again and someone enters behind her, disguised in a balaclava. Sarah suspects that the person is trying to frighten her, but before she can find out who it is, she is attacked…
Will and Josh arrive back at the base, but by now the storm is so strong they can’t see anything other than the guide ropes that connect the various buildings. Munro comes out to find them and tells them Sarah has gone missing. Josh suggests they go straight to the storage hut, but the guide ropes to that area of the base have snapped in the wind and it would be hopeless trying to fight their way through the snow while conditions are this bad. Will points out that if Sarah was in trouble she would have activated her panic button, so they decide to go back to the main building and try contacting her via the intercom system. Unfortunately there’s no response and the group realise she’s either asleep, unconscious or lost outside. Josh becomes frustrated as neither Will nor Munro seem prepared to do anything, but they warn him its too dangerous to go out and if he gets lost in the blizzard he’ll quickly freeze to death.
Just then, Sarah responds to Will’s call and tells him she was taken outside by the stranger, who stole her panic button and goggles. Somehow she managed to stumble back to the main storage hut, but Will deduces from her symptoms that she has hypothermia. He tells her to change into dry clothes and climb into one of the sleeping bags to get her temperature back up. They can’t get to her because of the storm but she should be safe where she is. She recalls that just after she was attacked she heard someone shouting outside, but she’s not sure who’s voice it was. Munro, Morgane and Jack join Will and Josh just as Sarah tells them that she thinks the voice could have belonged to Munro. Will tells Sarah to get some rest as there’s nothing more they can do for her now. Josh confronts Munro who protests his innocence and claims that she must have heard him calling for her earlier. Morgane reminds him that he attacked Will the day before and has been ranting and raving ever since. Jack thinks he’s dangerous and unstable, but Munro responds by saying he knows Jack has been plotting with Morgane for weeks. He’s seen them whispering in the corner on several occasions. When Morgane accuses him of being paranoid, he lashes out at her and the others grab him and escort him to his office. With Munro safely locked away, Will tells the others it may be more than eight hours before they can reach Sarah. Morgane points out that the guide lines between the buildings don’t just snap in the wind, and Will agrees that Munro must have cut them deliberately.
Much later, Josh and Will manage to reach Sarah in the storage hut and she calls out to them. There’s a heavy build up of snow outside the door so it will take them a minute to get through to her. Jack is checking on the condition of the plane and Morgane is keeping an eye on Munro. Sarah tells them her head is still thumping and everything in the hut is so dark she can’t see anything. They manage to open the door and rush over to greet her, and she’s shocked to discover she’s been trapped there for thirteen hours. As they check her for frostbite they’re stunned when she asks them to turn on the light. Josh points out that it’s broad daylight and Will realises she’s gone snow blind. It’s caused by unprotected exposure to the sun and the symptoms usually take eight hours to develop. He’s confident that if she only had limited exposure she should recover soon, but he can’t make any promises. He can help to relieve the symptoms, but it’s possible she may have been blinded permanently.
Just then, Morgane contacts them over the intercom to warn them Munro has escaped and appears to have set the main building on fire. Will urges her to get out before she’s overcome by smoke but they hear the sound of gunfire and Morgane cries out…then the intercom goes dead. Will tells Josh they need to go back straight away to fight the fire, so Sarah has to be left alone once again. A few moments after they’ve gone, Sarah hears the door opening and footsteps approaching. It’s Dr Munro…
Will and Josh find Morgane in agony from her gunshot wounds and they discover the radio equipment has also been destroyed. Will sends Josh to find Jack in the common room and make sure he hasn’t passed out from smoke inhalation. If Morgane dies, that will make Munro a murderer!
Sarah challenges Munro and accuses him of leaving her outside in the hope that her death would look like an accident. She thinks he’s going to shoot her, but he points out that guns are outlawed in Antarctica. He seems genuinely surprised when she tells him Morgane has been shot and she can tell from his voice that he doesn’t know anything about it. He realises she is blind, but she tells him she can just start to make general shapes out. He says he only wants to talk and admits that he left the note for her in her sleeping quarters, but only because he has information that proves Morgane discovered something very dangerous beneath the ice. Sarah thinks he’s referring to a seed pod, but he seems confused. He activates a Geiger counter and reveals that Morgane found uranium ore which is richer than the processed uranium found in nuclear power stations. Sarah’s immediate concern is that she’s been in the same room with it for over thirteen hours, but Munro assures her it’s safe as it’s stored in lead-lined containers. It was Morgane that chose the drilling site, which suggests she’s obtained old Soviet records relating to the Russian drilling operation in the 1950s. She knew what they’d found and had used Munro’s research project to get her hands on it. Munro had overheard her earlier, speaking on the radio to someone and discussing how much profit they could make from selling it, so he went through her belongings and found the Geiger counter. He suspects she was working alongside some of the researchers who left the base earlier, but a more likely suspect would be someone who could help her get the uranium off the base quickly. At that moment the door opens and Sarah hears a shot. Munro cries out…and then Jack approaches Sarah and taunts her for being an investigative journalist who can no longer see anything!
Will drags Morgane to safety and asks who shot her, but before she can answer Josh arrives to say the fire is spreading really fast. He can’t find Jack and assumes Munro must have already got to him. Morgane starts mumbling about the Book of Tomorrows and the End Days being upon them and that she wished she’d been able to see the prophecy come true. Just before she dies she reveals she is a member of the Crimson Chapter of the Orphans of the Future. Will drags a shocked Josh out of the building.
Jack orders Sarah at gunpoint to carry a crate to the plane. He reveals that he lied about the plane being out of action so he could stay the night and collect the uranium. He forces her to load the crate aboard and then get inside herself. Just then, Josh calls out to them and runs over, followed by Will. Sarah manages to warn them about Jack and he’s forced to admit to killing Morgane. He threatens to do the same to Sarah if they don’t keep back, but Josh wants to know what the Crimson Chapter plan to do with the uranium. Jack explains that he has no interest in the sect and he’s only in this for the money. Now Morgane is dead he won’t have to share the proceeds with anyone. While he argues with the others, Sarah is left unattended inside the plane. She remembers enough about what Jack showed her earlier to adjust the instruments in the plane. Jack climbs aboard and tells her she’s coming with him as his insurance. He starts the plane and it moves off, with Josh and Will powerless to stop him.
As the plane starts moving, Sarah reveals to Jack that she regained her sight some time ago and has been bluffing him. She takes the chance that his gun will be too frozen to work and she prepares to jump out. Jack calls her bluff and pulls the trigger - but the gun is jammed. They start to struggle and Sarah falls from the plane as it starts to pick up speed. Josh and Will rush to help her, but as they’re heading for the remains of the base she tells them she activated the fuel dump mechanism. Jack isn’t going to get very far. She’s curious to know why Josh asked Jack about the Crimson Chapter and he tells her about Morgane. It all starts to make sense - Morgane found the high grade uranium ore beneath the ice and planned to sell it on the international black market to raise funds. Jack was just in it for himself until he got too greedy and killed her. Will admits he suspected Morgane of something, but he had no idea what. That was why he tried to persuade Sarah not to come here. She still feels it’s a bit of a coincidence that a research project she was funding was being used as a cover for the Crimson Chapter. Everything always seems to lead back to her.
The main building collapses as they approach, but Will assures them the fire would have trigged an automatic distress beacon and they can expect a rescue mission to arrive by dawn. In the meantime they can shelter in the main storage hut. Something is still worrying Sarah. They estimate that Morgane was hoping to raise tens of millions of pounds - so what on Earth is the Crimson Chapter planning that needs so much cash?
Here are the headlines at midday. The international scientific community has been rocked by allegations that a climate research project in Antarctica was being used as a front for smuggling uranium. News of the scheme emerged when an Australian pilot crash-landed on the frozen continent and a rescue mission found the uranium among his cargo. The pilot is now being questioned by the authorities. Details of the scheme remain sketchy but early reports suggest those involved planned to sell the uranium on the black market, enabling the highest bidder to manufacture weapons of mass destruction. According to a source within the investigation, those behind the operation were mercenaries.
The Keeper of the Crimson Chapter discusses recent events with a colleague and concludes that her counterpart in the White Chapter must have pulled a few strings to keep Sarah’s name out of the headlines. The failure of their latest operation is unfortunate and it means they’ll have to go ahead with their contingency plan. Their sleeper agent in Antarctica was supposed to have arranged Sarah’s death and make it look like an accident, so she gives orders for him to be brought in to account for what happened. Either he carries out her orders or else she’ll be forced to intervene. The End Days are too close to allow a crisis of conscience by one of their sleepers to impede the great crusade. It is decided - Will Sullivan must kill Sarah Jane Smith or face the consequences of his failure!