In 1922, in a country south of Mexico embroiled in a turbulent revolution, the story unfolds around Emmet Keogh, an Irish patriot and seasoned political assassin. He finds himself coerced into a dangerous mission: transporting a truckload of Scotch whiskey for a ruthless English gunrunner, Jennings. During his journey, Keogh demonstrates compassion and courage by helping Father Oliver Van Horne, an American Catholic priest, whose vehicle has broken down over rocks and who is stranded in the rugged terrain. Their encounter sparks a series of events that will entangle their fates in conflict and violence.
When Keogh finally reaches his intended destination, he confronts a grim reality— the man he was supposed to deliver the cargo to has been murdered by soldiers under the command of Colonel Santilla. This group of soldiers is also attempting to assault a mute Aymara Indian woman named Chela. Keogh intervenes, risking his life to protect her, only to be captured and sentenced to hang before being rescued at the last moment by Van Horne, who arrives armed with a machine gun, eliminating Santilla's men and saving Keogh and Chela from imminent death. However, the soldiers’ leader manages to escape and report this incident to Santilla, intensifying the conflict.
Following their escape, Keogh, Van Horne, and Jennings are subjected to a brutal mock execution, where Santilla offers them a deadly proposition: to assassinate Tomas de la Plata, a figure living under heavy protection in a fortified region called Mojada. Santilla promises them equal shares of $53,000 in exchange for this dangerous task, emphasizing the potential reward if they succeed. Unbeknownst to the others, Keogh and Jennings are secretly posing as mining company employees, as de la Plata is eager to reopen a silver mine—a prospect that interests the trio. During their journey, Keogh encounters Nacho, an Aymara chief, and is reunited with Chela, who gifts him a necklace symbolizing their bond. An intriguing detail is that the Aymara society is matriarchal, and women like Chela are responsible for choosing their husbands; she and Keogh have, without his knowledge, become married.
As they settle in Mojada, Van Horne dedicates himself to cleaning and restoring the local church, aided by an orphaned choirboy named Pablito. Meanwhile, Keogh and Jennings attend a gathering at de la Plata’s hacienda. De la Plata, however, harbors a deep disdain for priests due to a tragic past: during Mojada's liberation, his father was brutally murdered, and his sister—who later committed suicide out of shame—along with his mother, were victimized by Santilla’s men while a corrupt priest remained passive. This history fuels de la Plata’s hostility towards Van Horne and other clergy.
Van Horne devises a plan to ambush de la Plata by holding a mass, which he announces will be performed at 4 p.m., hoping to lure de la Plata into a trap. When the priest's efforts are thwarted at the last minute, de la Plata spares Van Horne—a moment of mercy only granted because of his mother’s plea, though she prevents him from performing any priestly rites. The emotional scars run deep, revealing that the brutality inflicted upon de la Plata’s family has left him with an intense hatred for priests and the church.
The conflict escalates as Van Horne and his companions try to rally the townspeople through a series of religious ceremonies and acts of defiance. The next morning, some of de la Plata’s men are wounded in a skirmish, while the leader narrowly escapes. Soon, Nacho arrives, wounded himself, to warn them that de la Plata has taken hostages— including Chela and Pablito— and threatens to execute them one by one every half hour unless Van Horne surrenders. Tragically, in a brutal turn, de la Plata's second-in-command, Jurado, kills Pablito in cold blood, and Van Horne, driven by outrage and grief, decides to surrender.
Van Horne narrowly escapes death after a mistaken identity—believing he has killed de la Plata in a confrontation—only to realize the man he shot was a double. Keogh, Nacho, and a group of Aymara fighters launch a daring rescue, storming the compound with grenades and forcing their way inside. During the chaos, Jennings sustains mortal wounds while trying to protect everyone, and Jurado is fatally wounded by Nacho. Jennings sacrifices himself by blowing up with a grenade, ensuring their enemies are defeated. As the battle reaches its climax, de la Plata attempts to shoot Keogh but is shot by his own mother, Señora De La Plata, who has chosen to stand against her son’s evil. De la Plata stumbles and collapses near a stone cross tied to Van Horne, who manages to topple it onto his adversary's chest in a final act of justice.
In the aftermath, everyone rushes to tend to the wounded in a scene filled with relief and somber reflection. The church bells ring out, marking a new beginning, as Van Horne and Keogh—wounded but victorious—look on. Their story is one of courage, sacrifice, and the enduring fight against corruption and brutality in a land torn by violence.
