Professor Auguste A. Topaze (John Barrymore) is a simple, naïve schoolteacher with a good name and an impeccable reputation. When the wealthy and corrupt Baron Philippe de La Tour-La Tour (Reginald Mason) and his mistress, Coco (Myrna Loy), take advantage of the professor's good nature in a fraudulent business scheme, Topaze learns a harsh lesson on the consequences that exist outside the world of academia. He soon finds his sense of ethics and honesty being pushed to the limit.