In medieval France, a thief named Phillipe "The Mouse" Gaston (Matthew Broderick) escapes from the dungeons of the Bishop of Aquila through the sewers. He's almost caught by the Bishop's Guards, but is rescued by a knight named Navarre (Rutger Hauer), who needs his help.
Navarre tells Phillipe he needs him to get back inside Aquila so he can kill the evil Bishop (John Wood). Unwilling to go back inside, Phillipe runs and is captured by the Bishop's Guards, who injure Navarre and Navarre's hawk with crossbows in the process. However, Navarre again saves Philippe from the guards. He asks him to take the injured hawk to Imperius’ (Leo McKern) ruined castle for help. There Philippe learns that the Bishop put Navarre and his lady friend Isabelle (Michelle Pfeiffer) under a curse—the woman is a hawk by day and Navarre is a wolf at night—the two can only meet as humans at dawn and dusk. Phillipe decides to join Imperius to help the lovers break the curse.