Topher is desperate to find his beloved cat Ka when she disappears, leaving a single clue on his computer: TENOCHT*I*TLaN. When Topher follows Ka back in time, finds himself in the dangerous world of the Aztecs.

The people of the wondrous, floating city of Tenochtitlan believe Ka is one of their gods, but El Sol, a piratical Spanish conquistador, thinks she is a witch.

Can Topher save Ka from El Sol, rescue Pima, a girl the Aztecs want to sacrifice, and escape from Tenochtitlan before it is destroyed?