Father Maurice, a priest living in a residential college for priests in Rome, is called out one day to "exorcise" the devil from someone. The devil turns out to be in the form of a fun-loving man called Giuditta. What Father Maurice doesn't know is that this type of devil will turn his life around.
The film is a parody of Disney's Fantasia, though possibly more of a challenge to Fantasia than parody status would imply. In the context of this film, "Allegro non Troppo" means Not So Fast!, an interjection meaning "slow down" or "think before you act" and refers to the film's pessimistic view of Western progress (as opposed to the optimism of Disney's original).
Roman TV technicians Fabio and Enzo have been unable to find decent jobs. They decide to crack a safe at a jewelry in Milan. To get the layout of the store, they enlist a beautiful but unsophisticated young woman, Deborah. To find underground access to the store, they get help from a sewage worker. An obese trapeze artist is called for disarm the store alarms. The clever Mrs. Motta, old hotelier, is also involved. Will they succeed?
