Eight people wake up in a windowless room, tied to chairs by the ankles, eyes blinded. A voice tell them that among them only one person knows the code to leave the place, and that they need to be two and only two to use it on the code panels in the airlock protecting the only exit. The game will be to eliminate the innocents one to stay the last one alive with the one who planned all this. Furthermore, each and everyone of them has a reason to be here and a “special power”.

Once untied, the 8 strangers discover they don’t know each other, and that a kind of electronic heart with 8 buttons has been put in their chest.

The eight characters are: Matthieu (programmer), Kim (jobless), Charles (retired military man), Jenna (brilliant teenager), Fabien (medical intern), Lise (psychiatrist), Roxanne (works in marketing), Pierre (architect).

They meet each other. Fabien tries a code in the airlock, but smoke comes out of nowhere and makes him suffocate. The voice tells them that the next time there will be a wrong try, it will be cyanhydric acid: they won’t try their luck anymore. They explore the house and discover their electronic hearts allow them to unlock their dedicated bedroom. They are all the same except one which has 6 beds (for the six people supposed to die here). The 9th door (a storeroom) stays locked. The voice tells them by during the night, the bedrooms doors will be automatically locked. As for the eight boxes downstairs, only one they them opens: Charles finds a paper inside his box, which tells him what is his power. He refuses to tells the others what it is. Furthermore, they discover a gun and bullets under the stairs, locked away too. Matthieu realizes he knows Roxanne: they were neighbors in their university dormitory. Meanwhile, tensions rise up.

The second day, everyone tries to open his box, with no success. They understand Charles’ power is to unlock any box, but he refuses to open any. Matthieu tries to touch his electronic heart and discovers he can electrocute the others… but he panics and kills himself by electrocuting himself. The other bring him to the 6 beds bedroom and take his electronic heart, deciding they will keep it one after the other. Pierre confess he build the plans of the place, but that he doesn’t know anything more. The other discovers Fabien is the son of a rich media mogul. Lise tells she knows Kim, one of the patients, unstable and suicidal. And Charles knows Roxanne: he sympathized with her when she was a child living in the same neighborhood. He also confess he had to do some unethical experiments for the army.

Kim tries to kill herself with Matthieu’s hearts, but fails. In a crisis – and armed with a dagger – the tries to attack the others. While fighting, Charles breaks her neck. They take her heart and put her in the second bed beside Matthieu’s body. They open Lise’s box, but she takes the paper and eats it without reading it, since she doesn’t want violence to escalate. They understand Kim had access to weapons (the 9th room), and vote to see if they feel able to eliminate someone: the answer is “yes”. Charles, exhausted of all of this, tries to sabotage the thing so that everyone votes to get rid of him. They go explore the 9th room to check if there is anything that could kill someone “softly”. They find a robe, a plastic duck, a bottle of olive oil, and a kaki.

The next morning, Charles unlocks Jenna’s box. She takes and paper and keeps it on her without watching it. Everyone agrees on Charles’ demand, and they suffocate him under a pillow. They let him in his room, and Roxanne takes his heart.

The food supplies begin to go down. One evening, Fabien and Jenna have a discussion. He tells them that he does something more than his medical internship: his father gave him a job in his company; he has to develop new concepts for TV shows. He also tells him his father goes out with a younger Asian girl (possibly Kim). Jeena tries to have sex with him, but he refuses.

Jenna understand the olive oil is supposed to be used for a… human steak, when they have nothing else to eat. Panic arise among everyone. Lise goes to lock herself in her room and doesn’t come out. Finally, some days later, she goes see Pierre in his room during a night: she offers him an alliance by giving him Kim’s heart (to access the weapons’ room), and goes back in her room (her power is to access to the 8 bedrooms). The next morning, Roxanne discover some meat being cooked in the kitchen; driven by hunger and despair, she eats some before understanding it’s human flesh and that it’s a sick joke from Lise. Lise uses the panic in everyone to go out of her room and but a knife on Fabien’s throat. Finally, she stabs him and the other one stop her, before tying and gagging her up. Fabien survives, even if he is clearly weakened. Finally, Lise dies from dehydration. The four survivors play a bluffing game, won by Jenna who counted the cards, thus rising the animosity the others feel for her. Roxanne confess she had sex with Fabien to get his help and that she put the knife out of his body knowing the hemorrhage could kill him. Pierre tries to make everyone think he is the wolf by reminding he made the place. Fabien tells he had enough money to plan everything, and Jenna reminds everyone of the very high IQ. A new vote will take place. Roxanne tells she has aids. Finally, on everyone’s surprise, Jenna has “won” the vote. Indeed, Roxanne and Pierre being siblings, they made an alliance. Jenna unlocks the box containing the gun and the bullets, and kills herself. It becomes clear Roxanne knew the 7 other participants, et Fabien deduces from this he won’t survive. He gets the gun and kills Pierre.

The ending has several readings: either Roxanne is killed by a lost bullet, either she chooses to stay in the house. Fabien uses Pierre’s heart to close the lights, and probably unlock the main door, and leaves (but he also symbolically died since he had sex with Roxanne).

The epilogue uncovers the truth: if was indeed a TV show, in which everyone was responsible in his own way, even the watchers; furthermore, killing was never necessary: helping each other was possible all along…