At the Vélodrome d'Hiver, at the height of the sports competitions, the director of the house is found murdered. We also stole the recipe for the show. A swarm of private detectives, second-hand sleuths, embark on the most diverse tracks. Arrests pile up and the chase continues amid the non-stop games. The culprit will however be caught, red-handed, by a young inspector wearing a handsome mask.