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.
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.
Jean-Louis, Danielle's fiancé, a nurse, becomes blind following an explosion in the mine where he works. Coming from Lyon, Doctor Coudray, whose natural son Gilbert - who loves Danielle - dies while helping his father threatened by the person responsible for Jean-Louis' accident, will work to restore his sight.
