1981. The armed conflict in Central America rages. In El Salvador, a right-wing government and leftist guerrillas are deadlocked in a bloody fratricidal war. In the United States, a shift in public opinion sparked by reports of human rights violations threatens US military aid to the country, shifting the momentum in favor of a guerrilla victory. The military escalates the violence.

The small village of EL MOZOTE, in Morazán province, is a peaceful enclave of Catholics and Evangelicals coexisting in harmony. On the morning of December 10, government troops under the command of Lieutenant Coronel REYNALDO MONTENEGRO raid the village and massacre the entire population. Over a thousand people die.

JOSE GUEVARA, 12, hides in a filthy hole in the rainforest surrounding the village and survives the massacre. He is found days later by the guerrilla unit in charge of RADIO VENCEREMOS, under the command of AURELIO, the shrewd guerrilla leader.

Following Aurelio’s orders, the clandestine radio station moves constantly, broadcasting from different locations in the jungle, keeping one step ahead of Montenegro’s troops. The trauma of losing his family thrusts José into a deep depression resulting in the loss of his speech. ALMA, a courageous guerrilla sniper protects the boy. Aurelio and the political arm of the FMLN contact RANDALL WALKER, correspondent for The New York Times, and smuggle him into Morazán Province, with photojournalist SARAH MASON. The visit of the journalists to the site of the massacre allows Montenegro to locate and attack the elusive radio station, inflicting a devastating defeat to the guerrillas.

After a near-death experience José recovers his speech and reminds Aurelio of his objectives in taking up arms. Faced with the certainty that Montenegro’s death is strategic to the survival of Radio Venceremos, Aurelio and his guerrillas craft a new plan to eliminate him. Obsessed with the destruction of the rebel radio, and pressured by his higher-ups to silence it before the US Congress vote on the next round of military aid to the country, Montenegro falls into their trap and plummets to his death in his helicopter.