In 1973 Uruguay, the nation is under the oppressive grip of a civic-military dictatorship, with the National Army engaged in violent battles against the leftist Tupamaros group. Three courageous members of the Tupamaros—José "Pepe" Mujica (Antonio de la Torre), Mauricio Rosencof (Chino Darín), and Eleuterio Fernández Huidobro (Alfonso Tort)—are captured and confined as hostages in a prison controlled by the government. Over the next twelve harrowing years, the trio endures repeated transfers to various military facilities scattered throughout the country.
As mounting international scrutiny prevents the military from executing them, they resort to psychological torment instead. The hostages are subjected to humiliating petty rules and severe abuses, including solitary confinement and even a staged execution. In a rare show of compassion under pressure from the hostages' families, the military chief reluctantly grants a brief opportunity for the men to reunite on the prison grounds, but with an ominous warning to maintain silence.
In 1975, Pepe experiences a drastic separation from his comrades, being imprisoned in the dark confines of a grain silo. His isolation leads him to suffer from severe mental delusions, prompting haunting hallucinations of his mother. Meanwhile, in a different facility, Rosencof forms an unexpected bond with Sargento Alzamora (César Bordón), aiding him in crafting a heartfelt letter to a girl he admires. Eventually, the trio reunites and is transported to a hidden underground prison in 1978. Tragically, Pepe is thrust into complete isolation, spiraling further into despair as he clings to memories of his capture and grapples with the fear of being forgotten by time.
Their fate shifts as they are moved to another prison boasting improved conditions, granted special privileges in a deceptive tactic to mislead a visiting Red Cross delegation. However, these privileges are swiftly rescinded once the delegation departs. The discovery of a bar of soap with mysterious inscriptions in Huidobro's possession leads to intense scrutiny, ultimately exonerating him but triggering a grim remark from the military chief about his failure to eliminate them.
After a series of items sent by his mother are unjustly taken, Pepe disrupts a military event occurring close to his cell, resulting in an order for him to see a psychiatrist, who vows to highlight his dire situation. By 1980, the government faces a significant defeat in a referendum aimed at amending the constitution to entrench the military's power.
Fast forward to 1983, the hostages find themselves in another prison, where Rosencof encounters Alzamora, now serving as a chief guard. Alzamora, having married in the intervening years, expresses gratitude to Rosencof, which allows the three men increased freedoms under his supervision. The struggle culminates in 1985 when the military finally releases Pepe, Rosencof, and Huidobro among a wave of political prisoners during a general amnesty, leading to an emotional reunion with their families.
