Maurice (Walter Matthau) is an American priest living in a college community in Rome. When a local woman becomes possessed by the devil, Maurice is asked to perform an exorcism. The demon is exorcised successfully, but it turns out to be a scrawny, arrogant, wisecracking man named Giuditta (Roberto Benigni), who chooses to stay with Maurice instead of returning to hell. Giuditta, when not driving Maurice crazy with his antics, actually manages to fall in love.