In Mexico, the two globetrotting mice meet Wendy, a girl whose father is an archaeologist researching an ancient Mayan temple. What he doesn't know, however, is that the devious rat Notail Nogoodnik has sneaked into the very same temple to steal the Mayan treasure. The crook takes advantage of the Mayan mice's superstitions and appoints himself head of their people. But in the face of a lost plastic rat tail, Emily and Alexander immediately become suspicious.