L'Inconnu de Strasbourg.

Madeleine is with her lover, Jean-Paul, when her husband arrives home and catches the two together. Madeleine kills her husband and tells Jean-Paul to flee before the police arrive. After Jean-Paul drives away, he picks up a hitchhiker. When the car, stolen by the hitchhiker, explodes, police believe the dead hitchhiker is Jean-Paul. Madeleine takes up with Jean-Paul's brother, Bastien, while Jean-Paul, arriving in Strasbourg, is mistaken for the heir to a fortune. The detective on the case spends more time writing crime novels than investigating real-life crimes.