The Doctor and Jo arrive at Stangmoor prison. They are there as the Doctor is interested in a new development in the process of treating criminals. They enter the prison after the guard let's them in as observers from UNIT.

Things are going from bad to worse at the prison, where there is a riot over the use of the new process. Some guards open a cell, which contains a man called Barnham, the next man to undergo the treatment. He puts up a fight, but is eventually dragged away.

The Doctor and Jo take their seats for a demonstration of the Keller process. Professor Kettering, who is working on behalf of the creator of the machine Emil Keller, says the process involves removing the negative impulses from the brain. The Keller machine is activated, and the prisoner Barnham is given the treatment. Barnham reacts violently to the process, despite Professor Kettering insisting the treatment was a total success. Barnham is taken away to the medical unit to recover.

In the medical wing, Doctor Summers says that there is nothing much wrong with Barnham, despite the violent reaction. The phone rings, when Doctor Summers informs Kettering that there has been some sort of accident in the processing room.

In the process room, Summers examines him and pronounces him dead. Kettering suspects this a delayed shock from seeing the process caused a heart attack, which the Doctor doubts. He recommends to Summers that an investigation into the man's medical history and a post-mortem, which Summers sees to. Jo encourages the Doctor to talk to the Brigadier, but he wants to wait until the results of the post-mortem. Jo suspects that the Brigadier has enough on his plate with UNIT handling the security arrangements for the first World Peace Conference.

At UNIT HQ, the Brigadier is on the phone when they are given more to do. UNIT is asked to take charge of the transportation of thunderbolt, a missile. The Brigadier gives Captain Yates the job. The conference is so far running smoothly, but that is about to change, as a representative from the Chinese delegation, Captain Chin Lee has had some important documents stolen. She suspects the Americans, and asks that the person who stole the documents punished to the full. She says this puts the success of the peace conference in jeopardy as if there is any more trouble, then the Chinese delegation will withdraw from the conference.

Chin Lee goes outside the conference to a nearby park where she takes the documents that she reported missing and burns them. She hears a strange humming noise, and places her hand over a device underneath her ear. She drops the burning papers in a nearby bin and walks back to the peace conference.

Back at Stangmoor prison, the Doctor isn't convinced that the Keller process is safe and he doesn't like it. Doctor Summers then arrives with the post-mortem. The death was caused by heart failure. Kettering thinks this proves his theory corrects, but the Doctor thinks that the man was attacked by a hoard of rats and the shock killed him, especially after hearing the dead man had a fear of rats. The Doctor and Jo walk out and the governor insists that Kettering check the machine.

The Brigadier calls in Captain Yates, but there is no sign of Chin Lee's papers, despite turning the place inside out. It gets worse when the Brigadier receives a phone call from the Captain to tell him that the Chinese delegate is dead.

Professor Kettering is in the process room checking the Keller Machine when the machine activates. Kettering in terror and tries to turn the machine but find he can’t. An image of an ocean appears in front of him, and he tries to swim away, but his movements are consistent with going underneath the water. Some time later, Doctor Summers is checking on Kettering and finds that he is death. All the symptoms are consistent with death by drowning. The machine affects minds, and it is growing stronger. The Doctor orders that the machine be put out of use.

In the Chinese delegates room, the body of the Chinese delegate is taken away. Captain Chin Lee is complaining about the murder, but the Brigadier asks her everything about the incident. She informs him that she had a meeting with him at 12 p.m., she arrived punctually and saw the General dead on the floor. She then reported the death to the Brigadier. The Brigadier asks Corporal Bell to check the time of Chin Lee’s telephone call.

The Governor tells the Doctor that he will suspend the use of the Keller process and seal off the process room, but any further action on the Keller Machine would have to be taken with the backing of the Home Office. The Doctor says that he will work on the machine to make sure that it’s safe. The machine has been in near a year when Professor Keller supervised the installation; he had a rather attractive Chinese girl as his assistant.

Corporal Bell hands the Brigadier a piece of paper and double checks with Chin Lee phoned him without delay. She says she didn’t, but she actually rang at 12:24 p.m., he asks why she waited nearly half an hour before reporting the death.

In the medical wing, Doctor Summers is running some checks on Barnham. Physically he’s fine, but mentally is a different matter, as he doesn’t remember Doctor Summers. Jo walks in and asks about Kettering. Doctor Summers tells her that the autopsy revealed his lungs were full of water, he drowned in a perfectly dry room.

The Doctor is rapidly losing his battle with the flames until Jo comes in and she distracts the machine enough to let go of it’s hold on the Doctor. She tries to calm him down, but she can’t help asking questions. The machine picked up on a memory that the Doctor had of an entire world blowing up in smoke, which it turned on the Doctor. Having recovered, the Doctor reads the report on Kettering and asks Jo to take it to the governor’s office. Jo starts to take it up but is surprised when Captain Yates walks in insisting that the Doctor go back to London to help the Brigadier. After initially refusing, he goes with Mike and Jo walks out, closing the door to the process room.

Chin Lee is in a call box making a call and is watched from far away by Sergeant Benton. Chin Lee came out of the phone box and attacks Benton by using the Keller Machine. Benton faints and is helped by a passer-by. Chin Lee manages to escape, while Benton returns to the peace conference.

Benton tells the Brigadier what happened and tells him to go and lie down. The Doctor walks in and wonders what all the fuss is about.

There is a strange man interfering with some telephone wires as Benton walks out of the building. The strange man manages to fix it so that he can hear all the phone calls that UNIT make, and is listening in on a conversation between Captain Yates and the current holders of Thunderbolt. The strange man is the Master, and he gets into a limousine.

The Doctor agrees to help the Brigadier with the problems of the peace conference after he says that he will write to the home secretary backing up his recommendations that the Keller process be banned. They then go off to see the new Chinese delegate Fu Peng, who the Doctor thinks is Hokkien, but the Brigadier corrects him, saying he is Chinese.

The Master hears Captain Yates ordering some bikes and a jeep for the escort of Thunderbolt. While listening, he sees the Doctor and the Brigadier leaving the conference building.

The Brigadier and the Doctor meet Fu Peng with the new Chinese delegate refusing the hand of the Brigadier. The Doctor, on the other hand, welcomes him by speaking in his native language, Hokkien. The two of them swap pleasantries, much to the Brigadier’s annoyance.

More riots in the prison start as the machine activates. A man named Vosper is made to clean one of the cells, while in the medical wing, Summers is still examining Barnham. Doctor Summers explains to Jo that the machine has overreacted and withdrawn all the negative impulses from his brain, which leaves him as either an idiot or a saint.

Vosper manages to slip a gun under the pillows of the bed, and is sent out when Mailer, another prisoner is moved into the cell to await the sentence of the court, i.e., the Keller process. The guards keep an eye on Mailer, while playing a game of checkers.

The Doctor and Fu Peng continue to be friendly, always speaking in Hokkien, and the Doctor drags the reluctant Brigadier away, convinced that he has got nothing out of this meeting.

Mailer is whinging about the lack of the food, but when a guard with some food walks in, he grabs him and puts a gun to his neck. The guards hand over the keys to the cell and Mailer leaves.

The Doctor is suggesting that there are connections between all the events and the Keller Machine. Captain Yates gives the Brigadier all the details concerning the moving of the Thunderbolt, and the Brigadier is surprised to see that Yates is taking Benton. As far as the Brigadier’s concerned, is welcome to him after the incident where he managed to lose a Chinese girl in broad daylight. The Doctor is concerned at the mention of a Chinese girl, and says that it is imperative that she is found.

Chin Lee though makes her way to a limousine and she gets into it, where the Master greets her. The Master orders her to kill the American delegate, and then tells her to leave.

Having got out of his cell, Mailer is now leading the convicts whom is supervising the taking over the prison and Mailer wants some hostages. They go into the medical wing and find two perfect candidates, Jo Grant and Doctor Summers.

The Doctor is waiting for a call to get through to Stangmoor prison, but they’re having trouble with the lines. The Brigadier gets a more positive phone call; they’ve found Captain Chin Lee.

The attack on Alcott is interrupted by the Doctor and the Brigadier who manage to get the dragon away. Chin Lee then faints, while the Doctor checks that Senator Alcott is alive. He is, and Fu Peng finds the telepathic amplifier, which was picking up the impulses and transmitting them through Chin Lee’s mind. The Doctor believes the impulses came from the Keller Machine of Stangmoor prison.

Mailer’s riot continues, despite the police apparently surrounding the prison. Mailer ignores this and puts Doctor Summers and Jo in his old cell.

The Doctor tries to ask some questions of Chin Lee after she wakes up, wanting to know about her relationship with Emil Keller and her trip to Stangmoor prison.

Mailer goes into the cell with Jo and Summers in it after failing to find the governor to talk to him. Summers tries to attack Mailer, but he’s stopped and at gun-point is forced to send a message getting Mailer and all his mob a guaranteed safe route out of Stangmoor. He’s taken away to send the message, with Mailer encouraging Jo to get some sleep.

Sergeant Benton is having problems with the missile, and encourages the men to get on with it.

The Brigadier is asleep on his desk, when the Doctor walks in with Chin Lee and wakes up the sleepy Lethbridge-Stewart. He says that Chin Lee can cast considerable light on what’s been going on. The Brigadier though is interrupted by a phone call from Captain Yates, who is keeping him up to date on the problems with the missile, while the Brigadier tells Yates about the incident with Chin Lee. The Master sitting in his limousine hears this conversation, and when the Brigadier mentions the Keller Machine and Stangmoor prison, the Master instructs his chauffeur to drive him to Stangmoor prison.

Chin Lee tells the Brigadier that she first met Emil Keller as an embassy receptionist, and he invited her over to Stangmoor prison to show her the Keller process, as prison reform is a high priority in Peking. She met this man Keller many times, but she can’t remember anything about their meetings. It’s at this point that the Doctor realises that the Master is Emil Keller.

Summers appeals to the governor to talk to Mailer, but he refuses to negotiate with Mailer. However, he does inform the Brigadier of what is happening to Jo. Before that, the Doctor urges the Brigadier to release Chin Lee, as she’s not a criminal.

Summers again appeals to the governor, and this time he relents. In the middle of the riot, the mob hears that the governor is about to arrive and they start preparing for his arrival. Just after that, Barnham walks in, looking for Dr Summers, with Mailer ordering him out. Jo then attacks Mailer, and the guards start to take control of the prison again, with Jo handing Mailer over to the arriving Governor.

The Master has arrived at Stangmoor prison and meets with the governor. He asks to see the man that led the riot, Mailer. They go into Mailer’s cell, and the guards leave. Mailer tries to attack the Master, but the Master is quicker. The Master wants Mailer to cause some trouble and he's bought a suitcase full of bombs. They organise a plan and the Master asks to be let out, they then attack the guards and escape, killing four more guards along the way.

Summers and Jo are in the medical wing, and Summers is trying to make a call. The Master places a device on the telephone and it attacks Summers. They try and escape, but Vosper stops them.

The Doctor is waiting outside Stangmoor prison, and is eventually shown in. When he gets past the gates, Mailer waves a gun at him. They get inside the prison. When inside, the Master greets him and his help is wanted. The Master wants him to control the Keller Machine, while the Master takes the Thunderbolt out of UNIT hands and wants to use it to blow up the peace conference. The Doctor then escapes out of the window. He is pursued by Mailer’s mob, with 5 bullets been fired, all of them missing. He makes for the main hall of the prison, and shouts out to Jo and Summers. Jo and Summers respond, and he heads up there, unfortunately, a guard is there and he fires. The Doctor escapes by diving into the process room, where the Master is waiting for him.

The Doctor collapses in the chair while the machine affects the whole prison. The Master struggles to get into the process room. When he does, he presses a few buttons, which turn off the Keller Machine. He then checks whether the Doctor is alive and then gets a nearby stethoscope, but when checking his first heart, it has stopped completely, but his second heart is beating. The Master tries resuscitating him.

Jo and Summers are in the cell making a plan, but are interrupted when Vosper bursts in and says that Summers is being transferred to another cell. He initially puts up a struggle, but is dragged away.

The Master is repetitively slapping the Doctor across the face and eventually wakes up. The Doctor’s first words are that he can’t survive against the machine, as he knows what the secret is. Inside the machine is a creature, which feeds off the evil of the mind. Mailer then comes into the process room and the Master orders that he is taken away and put in the cell with Jo. Mailer drags the Doctor to the cell and throws him in it.

Jo is delighted at seeing the Doctor, but is concerned for his health and goes to fetch some water. At this point, the Master enters the cell and Jo is surprised to see him. All he explains is that the Doctor will tell him everything when he recovers and Master leaves the cell.

Jo bangs her fist on the door to try and get the guard’s attention. The guard relents and opens the door, where Jo appeals for some help for the Doctor.

The Master goes into the process room, and after initially shaking off the effects of the Keller machine, it eventually starts to attack him and the Master is struggling to cope with the affects of the machine. He tries to switch off but turns round to see an image of the Doctor taunting and laughing at him. The Master is terrified; he runs out of the room and bolts the door.

Doctor Summers examines the Doctor and diagnoses that the Doctor has been physically and mentally beaten up and is in some sort of coma. The only thing that the Summers can do is to hand him a tablet. At that point, Vosper takes Doctor Summers away. When he’s gone, Jo tries to get the Doctor to take the tablet, but refuses saying that it will kill him. He asks for some rest and then goes to sleep.

The Master is in the governor’s office where he is mopping himself down with a handkerchief. Mailer enters the office where the Master congratulates him. Mailer though, is curious why they don’t get out of the prison before light. The Master explains that they would have the army, the police and helicopters after them. He then turns off the light and explains what he wants Mailer to do with the Thunderbolt. He asks Mailer to hijack at it so that he can aim the missile at the Peace Conference in London.

Vosper comes into the cell with Jo, who is attending to the Doctor. She asks Vosper for some breakfast, and after some persuasion, Vosper orders one of the mob to get some grub. They both leave the cell. The Doctor then wakes up and says to Jo that they should make a plan to get out of the cell.

They make a plan, and they wait for the food to be delivered. When it is, Jo attacks the man carrying the food by lifting it into his face, the Doctor then picks up the tray and attacks the next guard by hitting him over the back of the head. They then escape from the cell. They get into the governor’s office and Jo can see a search party outside but they aren’t going to escape. Jo sees a projection of Thunderbolt and wonders what it is. The Doctor explains what it is and he hopes that Captain Yates is escorting it.

Mailer prepares all his troops at the place where they are going to capture the Thunderbolt. They all hide in the long grass by the side of the road. The escort arrives and Mailer’s troops starts shooting at it and Mailer’s troops are winning and UNIT has been firmly defeated. Yates tries to get a message to the Brigadier about the attack, but is shot down. Back at UNIT HQ, the Brigadier is concerned about Yates. They place the exact position the convoy was attacked and the Brigadier wants a mobile HW down there, a forensic team and a car to take him down there. He instructs Corporal Bell to continue trying Yates, but can’t get through as Yates has picked up a motorbike and has followed Mailer’s mob.

Captain Yates follows them to a nearby hangar. Mailer’s mob put the missile into the hangar. Yates decides to make a break for it and heads for the bike. When he’s on the bike, Mailer’s mob notices him and start shooting at him. One of the tires on Mike’s bike is shot and he crashes into some boxes.

The Brigadier has arrived at the scene where the convoy was attacked, and is currently attending to Benton, who didn’t see anything as it happened very quickly. The Brigadier is wondering where Captain Yates has gone and speculates that he may have followed them as there is a motorbike missing.

The Doctor and Jo are still in the Governor’s office and the Doctor is still wondering how to deal with the alien creature that is inside the Keller Machine. Jo looks out of the window and sees the Master leaving. The Doctor goes down to the process room.

Mailer is struggling and leaves the process room. Fortunately for the Doctor and Jo, the machine tries to follow him. The Doctor concludes that the machine must have detected a higher concentration of evil in Mailer. They go outside and Jo sees Barnham wandering about. They tell Barnham that they are going to escape and they take him with them.

The Brigadier is flying over Stangmoor and sees no sign of activity in the prison or of the missile. They decide not to land and will continue surveillance.

The Doctor, Jo and Barnham walk outside and see a UNIT helicopter. They try and get its attention and fails, and then they are found by some of Mailer’s mob. Barnham is successful in fending off the first attacker, but another wave come in and prevents their escape.

The Master is on the telephone to Mailer who is demanding that he come back to fix the Keller Machine. The Master tells him that he is too busy, but Mailer insists, threatening to run away and tell him where the missile is. The Master relents and puts the telephone down. He then wakes up Captain Yates who had been tied to a chair and tells him of his plans to use the missile on the peace conference. The Master also tells him that he is been kept alive, as he would be a good hostage should UNIT find them before the missile is ready.

The Doctor, Jo and Barnham enter the governor’s office with the governor’s chair been presided over by Mailer. Mailer orders Barnham out as he gives him the creeps. The Doctor wonders why Mailer is working for the Master, and Mailer says that he has been offered money, a pardon and a free ticket to anywhere in the world. Mailer tells the Doctor to make him a better offer, but he can’t and Mailer has them locked up.

The Brigadier and his current understudy, Major Cosworth make plans to take Stangmoor prison, which is where the Brigadier thinks that the missile is. They then get a report of a black limousine entering the prison, which they assume is The Master. They decide to take Stangmoor prison.

The Doctor and Jo are in a cell and are playing Checkers when the Master, followed by Mailer walks in. The Master starts to speak, but is quietened by first the Doctor when making a move and then Jo when she makes a move. Jo wins the game, with the Doctor claiming the game is too simple. The Master then gets down to business by asking the Doctor to control that machine, which he can’t. The Master then encourages him to help by saying it will save lives, but he still refuses. The Master then uses blackmail by saying that if he doesn’t agree to help him, then Mailer will kill Jo. The Doctor considers this, and says that there maybe a way to stop that machine, and agrees to help. They leave, with Jo staying behind.

The Brigadier is in the mobile HQ, where he and Major Cosworth are briefing the assault party on the effort to take over Stangmoor prison. When they’ve finished, Major Cosworth says to the Brigadier that it’s an excellent plan and has every chance of success. The Brigadier is relieved to hear this. In to the Brigadier’s office is Sergeant Benton who asks him to go on the assault party, and after a little bit of persuasion, the Brigadier enables him to join them. Benton then asks about Captain Yates but the Brigadier tells him there’s no news.

Captain Yates manages to release himself from the ropes that tied him to the chair, and is about to leave when he hears someone approaching the door. He pretends to be tied to the chair and be unconscious. One of Mailer’s mob walks in and tries to examine Yates, but he manages to throw him over the chair and then escapes.

The Doctor has built a loop of coil to throw around the machine which will have emit beta particles that are like the human brain. He asks the Master to switch on the power supply to full when he says from outside the process room. The Doctor walks into the process room and the Keller Machine starts activating and the machine is causing the coil to flame as images from the Doctor’s past fill the room. Struggling to keep control, the Doctor throws the coil over the machine and shouts to the Master to switch the power on. The plan works, and the Keller Machine is temporarily grounded. The Master then gives his congratulations to the Doctor, and then orders Mailer back to his cell.

Jo sees the Doctor relieved back and he’s exhausted at having worked on the Keller Machine. It is fixed for now. Jo is starving, and picks up bits of the breakfast that they knocked over while the Doctor tells Jo of a story about Sir Walter Raleigh.

The assault party arrives at the main gate of Stangmoor prison, and the Brigadier is dressed as a food salesman. After some persuasion, they let them in via the main gate, while some of the party get out of the van as quietly as possible, and attack the guards. The UNIT troops get involved in a gun battle with the prisoners. Meanwhile, Sergeant Benton is leading a secret underground assault on Stangmoor, and rapidly approaching the prison. In the battle, the prisoners are being picked off easily, despite their best attempts to hold off UNIT’s surprise attack, while the underground party is descending the walls of Stangmoor. UNIT has killed off all resistance, and ushers the van through saying they’ve got to find the Doctor.

The gun that goes off was actually the Brigadier’s gun, and it shoots Mailer. The Doctor confirms that he is dead. Benton walks in, and the Master has got away, and the Doctor informs the Brigadier that the missile isn’t here. Order is then restored to Stangmoor, with the prisoners put back in their cells, and Barnham is found, but Jo decides to look after him. She goes to get him some food. The Doctor and the Brigadier look at the map, but are interrupted by Captain Yates calling from mobile HQ. Yates tells them that they have Thunderbolt in an abandoned hangar outside Stanham.

The Master starts to make preparations to fire Thunderbolt, while the Keller Machine starts to break loose from it’s bonds.

Sergeant Benton is made Acting Governor while the Doctor is sitting to try and think of a way of stopping the alien creature inside the Keller Machine. The Brigadier is to head down to mobile HQ and join Major Cosworth so that he can mop up the Master.

The machine breaks loose of the bond, causing devastation in the process room and can now move about the prison. The machine claims it’s first victims since it’s release, killing two guards.

The Doctor is making some plans to destroy the Keller Machine, while Jo brings some food for Barnham. The Doctor and Jo then go off to deal with the Keller Machine, using the Doctor’s plan. The phone in the governor’s office goes off and it’s Dr Summers wondering if the medical supplies have been delivered. They have, while Benton tells Barnham he can go and talk to whom he likes. He wanders off.

The Doctor and Jo have just discovered the scene outside the process room. The Doctor imagines that the machine must have stored all it’s energy and blown all the circuits. They both go into the process room, which is, absent of the Keller Machine. The machine then comes back and starts attacking the Doctor and Jo. Barnham stands in the doorway of the process room, and despite the best efforts of the Doctor, he walks in and the machine stops attacking. The Doctor concludes that it is because as the creature feeds on evil impulses in the mind, it can’t attack Barnham, as he hasn’t got any. They are safe from the machine as long as Barnham is with them. The Doctor goes off to talk to Sergeant Benton, while Jo stays with Barnham.

The Brigadier arrives at mobile HQ, and is delighted to hear that the missile has an abort mechanism, which they may well use.

The Doctor is with Sergeant Benton, having given him a list of all the equipment he needs to destroy the creature inside the Keller Machine. The phone rings, and Benton picks it up, introducing himself as Acting Governor Benton. The Master asks `Who`, only to get a similar response. He asks for the Doctor, and he gathers that the tables have turned at Stangmoor.

Dr Summers goes into the process room insisting that Barnham is returned to the medical wing, but when he tries to take him away, the Keller Machine starts attacking them. They return Barnham to his seat, right in front of the Keller Machine.

The Doctor asks the Master does he intend blowing up the peace conference, and the Master does. The Doctor then offers to return the dematerialisation circuit of his TARDIS in exchange for the missile, which the Master agrees to on the guarantee that he alone will come, and none of his UNIT friends. The Master says that if they do, he will blow up the missile.

Dr Summers attends to other patients, and leaves Barnham to Jo.

The Doctor contacts the Brigadier to try and get him to cancel his attack on the hangar and to fetch the Master’s dematerialisation circuit. The Brigadier says don’t worry and ends the conversation. The Brigadier then orders Yates to clear the area within a 10-mile radius and for somebody to press the abort button.

The Doctor has gone back to the process room, where he is getting annoyed with Jo for pointing out that all they have is the machine, but the Doctor gets an idea which with the help of Barnham could destroy the Master and the machine at the same time.

The Master disables the abort mechanism in case anyone decides to be clever.

Barnham carries the Keller Machine out of the process room and they go off to the mobile HQ. When they arrive, the Brigadier informs him that their attempts to blow up Thunderbolt were unsuccessful. The Doctor is then handed the dematerialisation circuit, and is reluctant to hand it back, while the Brigadier can’t see an alternative, unless he has a better plan. The Doctor answers `Of course, I have a better plan`.

The Doctor is driving a black Police van to the hangar at Stanham, with Jo and Barnham in the back, with Barnham holding on tight to the Keller Machine. The Doctor pulls up and meets with the Master, and is hoping that he won’t try anything silly despite the unusual vehicle. He’s only doing that because Bessie has broken down. The Master then says his missile is ready for launch and asks if he has the circuit, and the Doctor takes it out of his pocket. The Master asks the Doctor to examine, but he doesn’t hand it over. The Doctor then knocks the gun out of the Master’s hand, while Jo and Barnham leave the Keller Machine there attacking the Master. They rush to the hangar and Jo tells the Brigadier that the Doctor is repairing the abort mechanism, while an incoming helicopter lands to take them away. The Doctor repairs the circuit and Jo lets them know. While running to the helicopter, they pass the Master, with Barnham staying to help him. This stops the Keller Machine from attacking the Master and he is able to get away in the black van that the Doctor used earlier, running Barnham over in the process. The Doctor and Jo see this and rush over to him and confirm he is dead. They both get in the helicopter, and fly away.

At mobile HQ, there is a countdown until the missile blows up with 20 seconds left. It gets to 10 and the Brigadier 10, 9, 8, 7, 6, 5, 4, 3, 2, 1 and the missile explodes, with the Doctor and Jo seeing the devastation from the skies as the fragile hangar starts to collapse.