In the time of the Aztec Empire, Yohualli Coatl - a young Aztec boy - experiences tragedy when his father and village leader, Toltecatzin, is murdered by Spanish Conquistadors. Yohualli escapes to Tenochtitlan to warn King Moctezuma and his high priest, Yoka, of imminent danger. Using the temple of Tzinacan, the bat god, as a lair, Yohualli trains with his mentor and assistant, Acatzin, developing equipment and weaponry to confront the Spaniard invasion, protect Moctezuma's temple, and avenge his father's death.