Jane is given a bracelet by an elderly admirer. He is in league with Cleaver, a suave crook, and the two plan to use Jane and the bracelet to smuggle diamonds into England.
La scène d'action embrasse Tanger, Toulon et la Méditerranée, où Pierre Fresnay, Rolf Wanka et Kim Peacock, respectivement capitaines de bateaux français, allemands et anglais, s'unissent pour sauver les passagers d'un bateau neutre sur le point d'être englouti dans un nuage de fumée empoisonnée dégagé par un navire de contrebande.
A husband-and-wife detective team look into the murder of one of her friends, whose father--a prominent scientist--has been kidnapped. They find themselves up against a sinister crime organization headed by a mysterious figure known only as "Z".