A team of Smithsonian researchers have stumbled across a lost walled Aztec city guarded by some evil spirits, including a "great flying serpent of death." As days turn to weeks, Susan Jordan, the daughter of the professor leading the expedition, assembles a team to rescue her father and his colleagues from the clutches of the ancient Aztec warriors and their horrible serpent god.

Five animals meet regularly to discuss their inner angst in a group therapy session led by Dr. Clement, a canine psychotherapist. The group includes Lorraine, a leech who suffers from separation anxiety; Cheryl, a praying mantis who can’t seem to keep a man; Todd, a pig with an eating disorder; Jeffrey, a bird with guilt issues; and Linda, an obsessive-compulsive cat.