In the near future, biochemical weapons cause a disaster that makes the air unbreathable. During
interviews, the president of the USA assures everyone that the priority is his citizens yet
the reporters keep mentioning some rumors about secret bunkers where they'll hide scientists.
Eventually most of humanity is wiped out by this tragedy, and the most important and intelligent
scientists of the country are put in cryogenic sleep in underground bunkers to wait until the
air is no longer toxic. There are dozens of these bunkers, and they're maintained by two engineers
that wake up for two hours every six months. In this particular facility, the engineers are
Bauer and Cartwright, and it's always Bauer who wakes up first. He feels a bit nauseous,
but he recovers quickly, unlike Cartwright who always wakes up with nightmares because of his
claustrophobia. Bauer teases him for a while before finally letting him come out of his tank,
which is a different model from the others. Afterward both men begin their maintenance tasks,
which include logging in at the computer to let the other facilities they're alive. Cartwright is
glad to see the other bunkers are doing well too, even if communication among facilities
isn’t possible. They also check the air on the surface, but unfortunately it's still toxic.
Their room has a board with pictures of their old life and Bauer likes to put tape
with the word "dead" on their friends' faces to remind themselves of the reality out there,
but Cartwright hates it and removes the tape every time. The engineers continue to check the
information on the computers and Cartwright begins to worry when he sees there has been seismic
activity because of the potential damage it may've caused. Bauer is creeped out by the sleepers,
so they agree Cartwright will check on them. While Bauer goes into a corridor to do repairs,
Cartwright takes the chance to look at a picture he's hidden behind the board,
only to suddenly turn around when he hears Abby. This is a hallucination Cartwright has about the
woman he loves, and he doesn't mind chatting with her when he's alone. After putting the picture
in his pocket, Cartwright goes to check on the sleepers, and it's revealed Abby is one of the
scientists there. Her hallucination appears next to her tank while Cartwright runs the
diagnosis and she insists Cartwright should tell Bauer about her, but Cartwright says he'll wait
for the right time. At that moment, Bauer joins him and begins complaining about the sleepers,
thinking it's a waste of resources and their lives to babysit a guy that knows some stuff about
reptiles. However Cartwright truly thinks the scientists are the future of humanity, and he's
calculated that they'll be sleeping for twenty more shifts. Once they're done with their duties,
the duo uses their remaining minutes to watch old tv recordings, play chess, and Bauer even
uses the bathroom for a date with Manuela. Abby visits Cartwright again, saying she looks forward
to being together again when he falls asleep. However Cartwright is nervous because entering the
tank is always hell for him - no matter how many times he's already done it, his claustrophobia
always triggers. As Abby tries to comfort him, Cartwright suddenly sees flames on her body,
and he realizes his tank is on fire. He rushes to call for Bauer, who comes out of the bathroom with
the extinguisher. The fire is successfully put out, but sadly the sleeping pod is now destroyed,
and Bauer has injured his hand in the process. To make matters worse, at that moment the two hours
end, meaning the lights go out and the air supply is cut off. Using torchlights and the little air
left in the room, the engineers read the manual and learn there's an emergency override, so they
take the stairs to find the right chamber. The emergency air supply valve is quickly turned on,
then the duo returns to the office to wait for the backup air to reach them. While they wait, they
share some details about their lives, and Bauer admits he used to have a wife and three daughters,
and he had to lie for the job because of the special requirements. Bauer had to watch how
the government sealed him in the bunker and his family was left out to die under false promises,
and Cartwright says he understands even if he doesn't have a family. At that moment the power
finally comes back and the air supply is restored, causing the clock to give them two more hours.
The engineers go looking for a spare pod at the storeroom but don't find any even if the manual
says spares exist. Cartwright realizes this may not be the only storeroom and checks the bunker
blueprint, which has a bunch of codes he doesn't understand. There's also a room named "long-term
storage" that they usually don't cover because it's sealed off, but Cartwright bets the spares
are there. The duo removes the seal and goes down a corridor they've never seen before, finding a
door at the end. Behind it, there's a locker room where Cartwright finds a broken security camera,
which doesn't make sense because their system isn't connected to this room. Bauer explains
it's probably a leftover from the time this place was a military facility. Searching deeper inside,
Cartwright sees Abby again, and she guides him to the box where he finally finds the spare pod. The
engineers quickly fix Cartwright's tank, but he's still afraid of getting inside. Bauer volunteers
to test it first and as soon as he lies down, he notices there must be a leak and the air is
getting thinner in there. Cartwright goes to check the pump and suddenly, the chamber sucks Bauer
down, suffocating him until he doesn't struggle in panic anymore. When Bauer is about to die,
Cartwright finally shows up and cuts the pod to free him. Thinking Cartwright tried to kill him,
Bauer furiously pushes him away, but Cartwright explains he was delayed because he couldn't find
a knife to break the pod open. Cartwright also reminds him that it should've been him,
which convinces Bauer it had been an accident. Since Cartwright's pod is destroyed now, Bauer
decides they must kill one of the sleepers to use their tank instead. Cartwright reminds him their
duty is to take care of the sleepers, but Bauer changes his mind by pointing out nobody can do the
caring if they're dead. While Cartwright prepares a morphine injection for the euthanization,
Abby shows up and asks him not to do it, she also says it's as simple as ABC. Getting an idea,
Cartwright announces he can't commit murder, and Bauer immediately begins arguing about this,
saying this is about survival. Then Bauer begins hitting him, but Cartwright pushes him away and
threatens him with an injection as he asks his friend to give his idea a chance. Feeling
defeated, Bauer accepts. The duo returns to the office and thanks to Abby's clue, Cartwright
realizes that the weird codes on the blueprint are the same ones on the computer, meaning each code
represents another bunker facility that may have more spare parts. Bauer thinks it's too dangerous
since they can't know if there are air leaks between facilities but Cartwright is willing to
take the risk. Then Cartwright puts on a hazmat suit that will provide clean air and a radio
that will keep him in contact with Bauer, who will guide him by following him on the security
cameras. When he enters the first corridor, he's shocked to discover a skeleton on the ground,
whose clothes and gun said it used to be a soldier. With only half an hour left, Bauer begins
fixing some old monitors in the office while Cartwright goes further inside the dark tunnels,
where he finds lots of floating blue dust from the airborne contaminant. After walking for a while,
Cartwright finally appears on the old security cameras, so Bauer begins labeling the fixed
monitors properly. Eventually Cartwright finds a door with a sign that confirms this is the ABC
facility. After struggling with the jammed lock, Cartwright comes inside and is shocked to discover
nothing here is working. Since he can't open the next door, Cartwright begins to feel hopeless, and
Abby appears to ask him not to give up. At that moment Bauer comes up with a solution: Cartwright
can enter the ABC facility by crawling through the air duct. The claustrophobia immediately kicks in,
but Cartwright swallows it down for the sake of his survival. As he moves through the duct,
he's disgusted to see there are numerous bodies here too and he has to crawl over
them. When Cartwright goes deeper into the duct, Bauer loses contact with him,
so he decides to use some tools to boost the signal. However when he grabs his toolbox,
he discovers his knife has been there all along and Cartwright possibly lied. Just to be sure,
he checks the security footage and is devastated to discover that Cartwright just stood next to the
tank doing nothing while he suffocated. Meanwhile Cartwright finally makes it to the ABC facility
and his radio begins working again. As he looks around, he discovers the facility is in complete
ruins and there are no survivors. There's also a hole in the ceiling that Cartwright uses to
look outside, only to discover the planet has been demolished by nuclear weapons a long time
ago. Next he checks on the sleeper's chambers, but they've also been destroyed. Cartwright gets
upset when he finally realizes that the computer showing that all the facilities were well had been
a lie to keep the engineers' sanity and make them believe they aren't alone. Bauer comments
they can't trust anyone anymore and puts the "dead" tape on the board again. While Cartwright
continues to explore, he comes to the conclusion his facility is the only one functioning, meaning
they are alone. Abby shows up to tell him he isn't alone, but at that moment Cartwright realizes he's
running low on air and begins running back to his own facility. Once he reaches the last corridor,
Cartwright goes through the decontamination process while Bauer shows up on the other side
of the door holding up his knife, pointing out his friend's lie. Cartwright swears he can explain,
but suddenly Bauer reveals he took the gun from the dead soldier and says Cartwright is a danger
to him and the sleepers, meaning he has to die. Desperate and afraid, Cartwright runs back into
the ABC facility, but the air is running out and he has trouble running. Abby shows up and tells
him to get back into the air duct because there's an alternate path he can take. As Cartwright
crawls his way through, Bauer berates him through the radio, telling him how much the betrayal hurt
and that he'll die soon if he doesn't come back. Cartwright just ignores him and keeps on moving
until he finds a path that takes him back to his own facility, where he quickly removes his suit
to breathe properly again. Then he tries to return to the office, only to suddenly be found by Bauer,
who opens fire. Luckily the shot doesn't land in the darkness, and Cartwright runs back to
hide behind the door. Bauer continues to follow him, ignoring Cartwright's pleas and reminders
that they're the last survivors because he's afraid that Cartwright will kill him in his
sleep. Using his radio, Bauer makes noise to find Cartwright through his own communicator, but when
he follows the echo he discovers Cartwright left his flashlight and his radio behind to trick him.
Meanwhile Cartwright locks the door behind him and goes to the infirmary to get some morphine.
He isn't sure if he should kill a dear friend, but Abby convinces him to do it or Bauer will
kill him first and they'll lose their future together. After getting the injection ready,
Cartwright comes out and discovers Bauer has managed to open the door and get inside. He
tries to sneak around carefully, but a shot to his shoulder takes him by surprise. Bauer comes
closer as he suffers for having to kill a man he considered family, and Cartwright tries to
explain he did it to protect his lover as he hands Bauer his secret picture. Then he starts talking
to Abby, which angers Bauer because it sounds like madness. Cartwright uses this distraction to jump
on Bauer and make him drop the gun, then he fails to hit him and runs away into the sleeper chamber.
Bauer recovers his gun and finds the picture on the floor, and something on it looks familiar.
He rushes to see the sleepers and confirms that Cartwright has been lying more than he thought.
It turns out Abby is Cartwright's wife, and that's the only reason why he cares so much about taking
care of the sleepers. Furious, Bauer threatens with killing Abby to make his friend come out,
but Cartwright surprises him from behind by injecting morphine on his shoulder. Bauer tries to
respond by shooting Cartwright, but the morphine kicks in and he falls to the floor in pain.
Cartwright intends to help him, but Bauer reminds him there isn't much time left so Cartwright
should go to sleep to keep taking care of his girl. Cartwright goes back to the office and uses
Bauer's chamber to go to sleep right before the clock reaches zero. Before losing consciousness,
Cartwright sees an illusion of Bauer playing with the chess set. Many years later, the sleepers
finally wake up from their cryo-sleep and begin looking around to see the current state of the
world. Abby searches for Cartwright and discovers he's now an old man, but she hugs him anyway.