The Mask of the Sun iTunes

The finding of a valuable ancient Aztec mask off the coast of Key West leads the Gabrieli brothers on a harrowing adventure. Mysteriously transported to the 16th century Inca empire where the fate of an alternate timeline lies in the balance, Mike Gabrieli finds himself pitted against a most formidable Conquistador. Will it pay to have reached too fast for gold?

Some additional time travel novels by Saberhagen:
A Century of Progress
After the Fact
Pyramids
Merlin’s Bones