Ai, a young prostitute specializing in costume fantasy, decides to have some fun by dressing as a police officer and questioning people around the site of a recent murder. She is invited to lunch at one house, only to discover that her host is the murderer, he is holding a family of three as his prisoners, and now Ai is his fourth. As time goes by, the killer's insanity begins to rub off on Ai and the family, until they begin to share in his warped view of the world.