Juan Oliver reports to work as a prison guard a day early. During his tour of the prison, a falling projectile knocks him unconscious and he is rushed to Cell 211. The projectile is revealed to be a diversion to allow the convicts to
riot and hijack control of the prison. Aware of the impending violence, Juan's colleagues flee and leave him in the cell. When Juan awakens in the midst of the chaos, he pretends to be a new inmate convicted of
homicide. He is brought to the leader of the riot, Malamadre, who takes Juan under his wing after Juan suggests variations to the riot which will better equip the prisoners for negotiation. In reality, Juan seeks to keep channels of communication alive with the other guards and an incoming
GEO team, who are preparing to storm the prison. Malamadre discovers that
Basque terrorists associated with
ETA are being held in the prison, and seeks to use them as a political bargaining chip during negotiation. As news of the riot become public, a succession of other riots and demonstrations in the
Basque Country follow. Afraid of political ramifications within the Basque Country, Spanish ministers hold back on exercising GEO interference, leaving Juan alone in the prison. Juan's pregnant wife, Elena, learns about the riot and heads for the prison; there, protestors related to the inmates fight with police, causing Elena to be hit by an officer. A television inside the prison shows the news footage to the prisoners, revealing to Juan that Elena was at the protest. Fearful for her safety, Juan attempts to contact the guards, while Malamadre demands information of all those injured. The authorities respond with a list of four names; infuriated, Malamadre decide to kill one of the ETA prisoners. However, Juan intervenes and suggest they cut off an ear, an act he is forced to perform. The authorities then provide additional information on the injured and Juan is told Elena is in the hospital, but recovering. Juan insists on talking to her but is rebuffed. Utrilla, the police guard who hit Elena, is suspended. Apache, an inmate close to Malamadre, learns the truth about Juan after contacting a friend in the police through a smuggled cell phone. He tells Juan he will give him a chance to defend himself before letting Malamadre know. Later, Malamadre has Apache tell Juan that he needs to speak to him. He shows Juan footage from a protestor's cell phone, showing Elena being beaten by Utrilla. Juan insists Utrilla be brought in the prison, where he is confronted by Juan. Juan again insists on talking to Elena, but he learns she and her unborn child have died. In response, the prisoners viciously beat Utrilla until he reveals Juan is a prison guard. He asks Juan to tell the truth; instead, Juan slits Utrilla's throat. Malamadre goes against advice to kill Juan, stating he does not believe Utrilla and that Juan's murder of Utrilla showcases his commitment to the prisoner's fight. Juan fails in a
suicide attempt in his cell. Malamadre receives a call from the police negotiator, who gives him Juan's employment records, confirming Utrilla's claim, and asks him to work with them in exchange for release. Malamadre still refuses to kill Juan. The government tell Malamadre they agree to his demands. Juan drags Utrilla's corpse in front of the government liaison and insists the government publicly agree, or they will kill the ETA prisoners. Malamadre tells Juan if the GEO team invades instead of a public agreement, he will either die, or kill Juan for his betrayal. As the GEO team quench the riot once they storm the prison, Apache kills Juan and severely injures Malamadre, who then works with the government against Apache. == Cast ==