Midnight's Lair
Richard Laymon
 The novel concerns a group of tourists who become trapped in an underground cavern after a fire destroys the exits. Darcy, one of the tour guides, takes a small group to try to escape by breaking into a portion of the cave that had been walled up years before. But when they attempt to breach the wall they accidentally release a family of cannibalistic savages that has been secretly living in the cave for over half a century.