In 1750 in the rain forest of central South America, Guarani Natives tie a Jesuit priest to a tree, push this crucifix into the river rapids, and watch it plunge over the majestic Iguazu waterfalls. Soon Father Gabriel (Jeremy Irons), another Jesuit, arrives to carry on the work of the martyred priest. After scaling the cliffs beside the falls, he takes out an oboe and begins to play. Guarani Natives emerge from the dense jungle and surround him. Through the music, however, they recognize him as a man of peace and take him into their midst. During a raid for Guarani Natives above the falls, the mercenary of slaves Rodrigo Mendoza (Robert De Niro) encounters Gabriel and learns that the Jesuits are building a mission there. Months later, Mendoza and Gabriel meet again. In a fit of jealous anger over losing his mistress, Mendoza has killed his brother, and he has sunk into a deep depression. Gabriel challenges him to have the courage to live and to choose a penance for his crime. When the priest, Fielding (Liam Neeson), and other Jesuits next climb the cliffs by Iguazu Falls, Mendoza is with them, dragging behind him a sack filled with his armor and sword. At the mission, the Guarani people, whom he had once persecuted, welcome him into their community. Eventually, Mendoza takes vows to become a member of the Jesuit order.