Commissioner Thomas simultaneously investigates the actions of an oil company, a theft and an assassination, and the kidnapping of a child with look-alikes.

The corpse of a man is discovered in Bercy. The murderer, his wife, acted out of fear of sexual diseases that her husband had contracted with a prostitute.

Against a backdrop of music hall and comedy acts, a Pigalle cabaret is famous for the activities of real and fake maharajas. One of them buys the cabaret and turns the checkroom attendant Annie into a real star. The maharajah then takes her to his kingdom, returning the place to its original manager.

The adventures of a Parisian boy and his little friends, who have taken on the role of detectives to track down the shady activities of Max, a disreputable individual who is courting Sylvie, the Parisian boy's young aunt... The discovery of a priceless necklace returned to its owner, will bring an upheaval in the destiny of little Jacky. "Born of an unknown father", at the age of twelve he finds an ignored home, a happier life in which his little friends will have their share, as well as Sylvie, who has got rid of Marx and will soon find a fiancé of higher rank.