Alcide Darbois, a small-time garage owner, and his sister Ursule come into a fabulous inheritance and become powerful industrialists. The cars they make a re very successful on the French market. Now a bit of a snob, Alcide decides to marry his daughter Suzanne to Marquis Gaëtan de la Michodière, but the young lady is actually in love with Bégonia, her father's chief worker. A car racing event will resolve the situation.

After a deadbeat patron at his restaurant gets special care from the cops who think the man has amnesia, the maitre d'hotel decides to pretend he too has amnesia. He is claimed in turn by an aristocrat family and by trapeze artists.