Zombies, demons, and a mad doctor await a bus-load of folks looking for a tour of Aztec ruins. Father O'Sullivan is a Catholic priest who has lost his faith in God and who cannot forget the nun with whom he once had an affair (and a son). O'Sullivan serves as tour guide for archaeological student Cal, New Agers Wilbur and Clarisse Lemming, runaway Laurie, and tourists Dozois and Frost on a bus trip to Mexico. No one is more surprised than O'Sullivan when his love, Tessie, also boards the bus with her bratty son Ivan. In Mexico, Cal reveals his knowledge of a crucial ancient text, just in time for the Day of the Dead festivities. Meanwhile, evil Dr.