La nuit s'achève

Young Monique leaves the preventorium where Doctor Delaunay has lovingly cared for her. A painful return. Her mother Denise lives with Eugène, a handsome, disreputable young man who's easy to please and, on occasion, won't hesitate to steal. He hangs around Monique, excited by her freshness, until the day he is shot on suspicion of the disappearance of a mobster. Monique is reunited with Dr Delaunay, much to the satisfaction of her guardian Gilbert, known as Patte-en-moins, owner of the local bistro.

A rich businessman, threatened by his pregnant mistress, decides to make him marry a man who falls in love with his daughter.

Although suspected and hunted down by policeman Sherlock Coco and inspector Hector, the Pieds Nickelés (Croquignol, Filochard and Ribouldingue) manage to save the legacy of Monsieur Miradoux, who will be very grateful to them.

Tongues start to wag after a famous Parisian music hall dancer is rushed to hospital after being found poisoned by arsenic at the Concert Mayol.

Sherlock Coco, famous detective, tries to thwart the machiavellian plans of the trio of shock. Croquignol, Ribouldingue and Filochard must be extra vigilant, but the profit motive is too strong. As a corollary, the famous pink diamond is also of interest to their legendary enemy, Jo Papillon. But always inventive, they will work out multiple scams and tricks to reach their goals.