In 1519, Pedro, a Franciscan priest, sets sail from Cuba with Hernan Cortes' brutal expedition to South America. Though filled with passion for adventure and converting native peoples to Catholicism, Pedro is unprepared for the shocking barbarity he is about to encounter. Accompanying Pedro is his friend Aguilar, who spent eight nightmarish years enslaved by natives after being shipwrecked. As the journey to Mexico City grows increasingly treacherous - fraught with disease, deprivation, and attacks - Pedro and Aguilar bear witness to scenes of unimaginable cruelty. They stand amazed by the intelligence and charisma of King Montezuma and the exotic sophistication of the Aztec capital with its ornate temples decorated in thousands of sacrificial human skulls. Yet beneath the surface beauty lies a dark terror: cages of men, women and children being fattened for ritual sacrifice, their beating hearts cut from their chests as offerings to the gods. As the campaign unfurls, Pedro and Aguilar are shocked by the brutality of their own countrymen. The ruthless exploitation of natives causes them to question their purpose here. Are they true men of God or merely instruments of Spanish greed? When fellow conquistador Alvarado orchestrates the brutal massacre of Aztec nobles at the feast of Toxcatl, Pedro and Aguilar are forced to make an existential reckoning. Their encounters with local people lead both men to reexamine every aspect of their lives and reconsider what they once thought was their higher purpose.