Brooklyn plumbers Mario (Bob Hoskins) and Luigi (John Leguizamo) are about to be shut down by a shady construction company, and when the firm's henchmen see that Luigi has fallen for a young student named Daisy (Samantha Mathis), they kidnap her -- and take her to another dimension. Vowing to track her down, the boys soon find themselves trapped in a bizarre parallel world ruled by a dinosaur-like despot named King Koopa (Dennis Hopper).