The film follows the twelve-year incarceration of members of the Tupamaros, a far-left urban guerrilla group active in the 1960s and 1970s, nine of whom were held as "hostages" between 1972 and 1985. It dramatises the experiences of José Mujica, Mauricio Rosencof and Eleuterio Fernández Huidobro. Mujica later became the 40th president of Uruguay from 2010 to 2015.
As the military is unable to kill the men owing to international pressure, it decides to torment them mentally instead. The hostages are subjected to petty rules and abuses, including solitary confinement and a mock execution. Under pressure from the hostages' families, the military chief permits a brief reunion in the prison grounds, but warns the men to be silent.
In 1975, Pepe is separated from the trio and held at the bottom of a grain silo. After a prolonged period, he experiences mental delusions and begins hallucinating about his mother. In another prison, Rosencof strikes up an acquaintance with sergeant Alzamora, and assists him in composing a letter to a girl. The three men are reunited and transported to an underground prison in 1978. Amongst the three, Pepe is locked up in complete isolation in his cell, worsening his condition. He relieves the memories of his capture and fears that they will be forgotten in the years to come.
The hostages are shifted to another prison with better conditions and given special privileges in a ruse to fool a visiting Red Cross delegation, which are revoked when the delegation leaves. During the process, a bar of soap with inscriptions is discovered in Huidobro's possession. He is subjected to questioning which exonerates him of any malicious intent, though the military chief expresses regret in not having killed him.
After items delivered by his mother are misappropriated, Pepe causes a commotion at a military event held near his cell, and is ordered to see a psychiatrist. She promises to raise awareness of his condition. In 1980, the government is defeated in a referendum to amend the constitution to provide the military with a leading role.
In 1983, the hostages are returned to another prison, and Rosencof meets sergeant Alzamora, now a chief guard. Alzamora reveals that he is now married and expresses gratitude to Rosencof, allowing the three men a greater degree of freedom under his custody. In 1985, the military releases the three men amongst other political prisoners in a general amnesty, and they reunite with their families.
