From publisher blurb:
"According to the Sentinel, renegades have penetrated Cuba sometime in 1519. As near as we can guess, the band of time-hoppers joined the Spanish conquistador, Hernan Cortes, who is on his way to conquer Tenochtitlan, the capital of the Aztec Empire. You probably know the place better by its later name, Mexico City. Now these renegades are probably after the legendary treasure of Moctezuma, the Aztec king. Of course, we can't be absolutely sure there's no other plan afoot." So goes another mission briefing by John Watkins, Commander of the Earth Specialty Division. Somehow, you're sure this won't be as simple as it sounds.