Mr. Topaze (Arnaudy) is a hard-working, honest, scrupulous teacher at a school run by a corrupt principal. When he fails to raise the grades of the daughter of a wealthy patron, he's fired, only to soon be hired as a "tutor" by the mistress of a local politician. This is merely a ruse, to get Topaze's honorable name attached to a dodgy business deal. Ever a man of trust and honor, Topaze is the last to twig, but, once he gets a taste for ill-gotten gains, he begins to settle old scores.