Strange things are happening in the small town of Breuil-le-Château. Provisions from the black market are stolen regularly and wealthy young men, including the squire's son, start vanishing... Ransom demands are sent but with an illegible signature. The investigation is trusted to Ducreux, the local police brigadier. He is assisted by Carlier, a film director in search of locations for his next movie, who has been mistaken for a police inspector from Paris. The two men will have more than their share of surprises.

The adventures of the famous Joseph Rouletabille, an adventurous young journalist, gone to solve a murder in the south of France. He puts an end to the conflict between two rival bands for the possession of a revolutionary metal, belenium.

A wealthy banker, bored with his life, heads to the Latin Quarter of Paris where he pretends to be a struggling artist. He falls in love with a student from the Sorbonne and moves into the same boarding house as her while continuing his pretence of poverty.

Rouletabille's fiancée, a young journalist always on the lookout for an investigation to solve, tells him how she has just suppressed a spy. Marriage is in question...

For years now, Chief inspector Gustave Picard has been trying to bring down Salviati, the dreadful leader of a drug-selling gang. Lucienne Préville, an informer who works for him, has infiltrated the gang but her position is dangerous. On the other hand, Scoppa, Salviati's former right-hand man, has started challenging his former boss. Will Salviati, the brutal public enemy, clear off at last?

An Oriental villain named Halloway is called in by wealthy oil interests who want to destroy a dam project for hydroelectric power that may threaten their profits.