In a prison known as the "Vertical Self-Management Center", Goreng wakes up in a concrete cell with the number 48 on its wall. There's nothing but a bed and a sink for him to use and a hole in the middle of the floor, which his cellmate Trimagasi calls "The Pit". There are hundreds of floors like theirs, all of them with two prisoners using fake names assigned by the management. Every day, food is lowered on a platform through the hole, and you have two minutes to eat as much as possible before it leaves to a lower floor. The lower you are, the fewer chances you have of eating anything. At the end of each month, prisoners are shuffled and sent to different floors.
When Goreng sees the platform for the first time, he decides not to eat because he isn't hungry, and he'd rather leave food for the lower levels. After eating as much as he can, Trimagasi spits on the table, knowing people above probably do the same. Goreng decides to keep an apple for later, but after the platform leaves, the cell begins to feel extremely hot. It turns out that keeping food is forbidden, so Goreng has to get rid of the apple or they'll burn to death. This makes Goreng think about the interview he had before entering the place, when he had to sign a paper accepting the fact he can't get out until the agreed period is over. Every prisoner has a choice to bring one item with them, and Goreng chose to bring a copy of "Don Quixote".
Goreng came here voluntarily, he'll spend six months in exchange for an accredited diploma. The next day, Goreng refuses to eat again when the platform comes, and Trimagasi thinks floor 48 is wasted on him. Goreng asks Trimagasi for his story, and Trimagasi explains it all started with a television ad. He bought an extraordinary knife that he saw on tv, but only a few days later, they released a new ad promoting an even better knife. This made him so furious that he took the tv and threw it out the window, killing a guy that was passing by. Trimagasi was given a choice between a psychiatric hospital and the hole, so here he is. The lowest he's gone was 132, thus he knows there are more floors than that because he could see them below.
No food reaches the lower levels, and a month down there isn't that bad, the problem is when you get two lower levels in a row. Goreng is scared of this possibility and tries to talk to the people on the other floors to ask them to ration their food, but he's ignored. Trimagasi replies by pissing into the lower floor, he also reveals that the item he chose to bring with him is the knife he bought from tv. The next time the platform comes by, Goreng finally begins to eat. He also sees a person from the upper levels fall through the hole, and Trimagasi says this is very common but nobody will do anything about it. Trimagasi tells Goreng about all the floors he's been on and mentions they'll be together next month. Goreng realizes that cellmates are kept together when they're shuffled and finally understands Trimagasi ate his previous cellmate when he was on the lower floors.
When the platform comes by again, Miharu is sitting on it. Goreng worries about her because he notices she's injured, but Trimagasi tells him to ignore her. Miharu comes down the hole once a month to look for her missing child, she also kills every cellmate she gets in order to have more chances to be paired with her child the following month; the guy they saw falling was probably her victim. Trimagasi then explains that unlike her, he never killed anyone, he just ate the body that fell on his floor. When the platform goes to the next level, the prisoners try to take advantage of Miharu. Goreng yells at them to leave her alone, but it isn't necessary: Miharu just kills them and returns to the platform. When the month reaches its end, the prisoners are put to sleep with gas and shuffled around. When Goreng wakes up, he finds himself tied to his bed on floor 171. Trimagasi explains he tied Goreng up because he's younger and stronger, so Trimagasi has to protect himself. Screaming can be heard from the other floors that indicate people reacting to their new levels, and when the platform comes, there's not even a crumb left. After eight days, Trimagasi announces it's finally time for him to get some food. Ignoring Goreng's pleas for mercy, Trimagasi uses his knife to get some meat from Goreng's thigh, but before he can eat it, the platform arrives, bringing Miharu with it. Miharu remembers how much Goreng worried about her and jumps on Trimagasi, attacking him with his own knife. Then she frees Goreng and hands him the knife so he can use it to finish Trimagasi off.
Goreng passes out after that, and he wakes up later to find himself on the bed. Miharu has bandaged his leg with a piece of bed sheet, and she's now eating Trimagasi. She brings some meat to Goreng who accepts after some hesitation, she also brings him some water before leaving on the platform without a word. Days pass and Trimagasi's body begins to rot, giving Goreng the chance to feed on worms too. Goreng also begins hallucinating, seeing Trimagasi's ghost judge him as he eats. At the end of the month, gas takes over the cell and Goreng dreams of being with a woman again while Miharu watches. When he wakes up, he discovers that the one licking him is a dog. To Goreng's shock, his new cellmate is Imoguiri, the woman that did his interview when he volunteered to enter this prison. The dog is the item she chose to bring with her, and they're now on level 33.
Goreng remembers the day of the interview and how Imoguiri made creepy pauses between questions. In the present, Imoguiri explains she volunteered as Goreng did, and that she didn't know people died here. As far as she knows, there are two hundred levels, and when Goreng explains there isn't enough food for all the people here, Imoguiri points out that the amount of food would be fine if people only ate what they needed. Something that fosters a spontaneous sense of solidarity needs to happen, but Goreng finds the idea ridiculous. He does wonder if change could be achieved by the death of a child, but Imoguiri's sure that company policy doesn't accept under-16s.
When the platform brings them food, Imoguiri only eats what she needs, and after giving some to her dog, she begins preparing two rations of food. Once the platform reaches the lower level, Imoguiri tries to reason with the prisoners, telling them to eat the rations she prepared and make two more for the next level to pass on the message. Obviously she is completely ignored, and Goreng points out that the Administration doesn't actually want solidarity to happen. Imoguiri hates that Goreng thinks all administration is bad because she worked for them without issues, but Goreng replies that being a former worker gave her the privilege of choosing her cellmate. Imoguiri doesn't give up and keeps on trying to ration the food every day, but she continues to be ignored by the lower levels. Two weeks later, Goreng finally gets tired of all her yelling and tells the people that if they don't follow Imoguiri's instructions, he'll relieve himself on the food every day and they'll have to eat poop. The threat works and the prisoners start passing the messages to the lower levels. Sometime later, the platform comes down with an unconscious Miharu on it.
Goreng and Imoguiri put her on a bed and take care of her while the dog steals some food. Once the platform leaves, the cell begins feeling extremely cold, and Goreng has to chase the dog to take back the food he stole before they're killed for breaking the rules. In the evening, Goreng leaves the bed to Miharu and sleeps on the floor, only to wake up to find the girls fighting - it turns out Miharu killed the dog to eat him. The next day, Miharu leaves on the platform. Goreng tells Imoguiri about Miharu's search for her child, but Imoguiri explains Miharu came alone ten months ago. She was an actress with no family that volunteered to come just like Goreng. Imoguiri sent people down here without knowing how bad it was, and she's been fighting cancer for three years. When she discovered she lost that fight, she volunteered to come because she thought she could make a difference, but she doesn't care anymore. On their last day on floor 33, Goreng tries to make Imoguiri eat something because they may not have food tomorrow, but Imoguiri is too depressed to leave the bed.
The next morning, Goreng wakes up to discover he's on floor 202, meaning there are more levels than Imoguiri knew about. Such revelation was too much for Imoguiri to handle and used her bed sheets to end things for herself. At that moment, Trimagasi's hallucination appears again, wondering if Goreng will eat his new friend. This time he's joined by Imoguiri and her dog, who insist he should eat her body. Goreng tries his best to ignore their constant rambling, and he tries to keep himself busy with other things: he tricks his stomach by eating pages of his book, and he takes a plate shard to start counting the days on the wall. Eventually the hunger becomes too much though, and Goreng finally begins feeding on Imoguiri while Trimagasi guides him on where to cut. Sometime later, the next shuffle comes and Goreng is pleased to discover he's on floor six.
The person on the other bed is Miharu, who comes after him with a knife, but this turns out to be just a dream. Goreng's new cellmate is actually Baharat, whose chosen item was a rope. Baharat is very excited because he thinks he can climb all the way to the top from here, and he asks the people on level five for help. The couple above teases him before accepting to grab the rope, but when Baharat starts climbing, the other prisoner lowers her pants and defecates on Baharat's face. Shocked and disgusted, Baharat lets go of the rope and falls, Goreng catches him just in time but the rope is lost in the hole. When the platform comes, they have to eat while listening to the prisoners on level five get frisky. As time passes, the hallucinations of Trimagasi and Imoguiri show up again.
Trimagasi says Goreng is doing great because he only has one more month to go, and Imoguiri reminds him that change never happens spontaneously. This inspires Goreng to think of a plan, and he asks Baharat for help. They should jump on the platform with whatever weapon they can find, and make sure people ration the food so that everyone can eat. Goreng did the math when he was on floor 202, and judging by the time the platform takes to move, he thinks there are around 250 levels, which should be doable. Baharat accepts to work together and they break a bed to use its pieces of metal like weapons. The two of them jump on the platform and go to level 7, where Goreng points out they shouldn't allow the prisoners to grab anything.
These people ate yesterday and will eat tomorrow for sure, so they should only start handing out food after level fifty, which are the people having trouble. Baharat hesitates because these prisoners are his friends that helped him climb up some weeks before, but as soon as the old man reacts furiously, Baharat sees Goreng's point and begins helping him keep everyone away. The pair keeps going down while threatening people to keep the food untouched. After a few more floors, Baharat is shocked to come across Brambang, an old wise man that Baharat respects. Brambang approves of what the boys are trying to do, but he points out that the Administration doesn't have a conscience and won't care if they succeed, but perhaps the workers on level cero will, so they need a symbol. Baharat and Goreng choose the panna cotta because it's a very luxurious dish and will cause quite an impression if it arrives untouched to the bottom. The mission continues as they keep going down, keeping the panna cotta safe while keeping people away with threats. Once they reach level fifty, Baharat and Goreng begin handing out rations of food, and people are extremely grateful. On level 97, they find a sick old man and a mentally disabled boy. Goreng tries to feed the old man some soup, but the boy tells them not to bother because he'll kill the man later anyway to feed on him.
The next level only has a body on it, and Goreng guesses this is where Miharu woke up. The platform doesn't stop here because there aren't any living people, which means Goreng's calculations were wrong and there are more than 250 floors. On the following floor, they find two men attacking Miharu. One of them has a sword and the other is huge and burly, so when Goreng and Baharat jump in to help the girl, it is extremely hard to defend themselves. Baharat manages to get his guy first and then he helps Goreng kill the big man, but unfortunately it's too late for Miharu, who is already dead. Goreng wants to mourn her, but Baharat drags him back on the platform before it leaves them behind. The two of them keep going down and handing out food to the prisoners they see, although many floors only have dead bodies on them. Eventually the platform stops at level 333, which seems to be the last one.
At first they think it's empty, but there's actually someone hiding under the bed: it's Mali, the missing child. Baharat and Goreng approach the kid, and as soon as they leave the platform, it starts going down again. Goreng asks Baharat to throw the panna cotta into the hole, but Baharat refuses. To their surprise, the room doesn't get hot or cold to punish them, and after lots of hesitation, Bharata gives the panna cotta to Mali. The three of them stay on that floor, and Goreng keeps being haunted by Trimagasi, Imoguiri, and now Miharu as well. Suddenly Baharat agrees with the ghosts, telling Goreng that the girl is the message, and when Goreng wakes up, he discovers Baharat died because of his bleeding injuries.
The next time the platform comes, Goreng brings Mali with him and they're lowered into floor cero, which is completely dark and empty. Trimagasi appears to tell Goreng to come off the platform because he isn't part of the message, and together they watch the platform go up with Mali, hoping that she will show the abusers above the reality of the situation.