Unworthy Sacrifice

The Aztecs are attempting to win the gods' favor by performing ritual sacrifices when one of the sacrifices goes horrifically wrong. In order to avoid a divine curse they are forced to perform a terrifying ritual.
The Conquistadors find an Aztec city defenseless and in the aftermath of what appears to be a civil war. What they discover is far worse and now must contend with a problem that could threaten the entire Spanish army.