Nobleman Rainiero, Sidonia's duke son, comes back home with his friend Renzo. Soon after arrival, Renzo will get in a big trouble and he will be forced to choose between going to church for marriage or going to prison.

Mr. Topaze ('Peter Sellers' ) is an unassuming school teacher in an unassuming small French town who is honest to a fault. He is fired when he refuses to give a passing grade to a bad student, the grandson of a wealthy baroness. Castel Benac (Herbert Lom), a government official who runs a crooked financial business on the side, is persuaded by his mistress, Suzy (Nadia Gray), a musical comedy actress, to hire Mr. Topaze as the front man for his business. Gradually, Topaze becomes a rapacious financier who sacrifices his honesty for success and, in a final stroke of business bravado, fires Benac and acquires Suzy in the deal. An old friend and colleague, Tamise (Michael Gough) questions him and tells Topaze that if what he now says and practices indicates there are no more honest men.

Reported missing in 1940, Jacques Ledru comes back to Strasbourg as Martin Schmidt. He tracks down his wife Genevieve, but she's remarried and has taken the head of his shipping company. She and her husband will do anything to get rid of Jacques and keep his company.

When a stranger enters a quiet, country town and is seduced by a sensuous married woman he unwittingly finds himself at the centre of a storm of sexual guilt and murder.