Nightclub singer Della Mason witnesses a murder and is forced by the killer to flee with him from the scene of the crime. Escaping from the gangster, she secretly boards the ship of Captain Josiah Storm, a woman-hater, and the ship sails from San Francisco headed for China. Della is discovered by Jim Benton, the ship's first mate and he pleads her case to the captain. He leaves her in under the protection of Minnie at "Minnie's Joint in Shanghai, until her innocence can be established.

Police detective Lanny resents the ongoing interference of the local FBI branch. Hoping to show up the feds, Lanny tackles a baffling espionage case. Things heat up when reporter sweetheart Ollie is framed for murder.

On his way to a post as special adviser of the new parachute troops of the French Foreign Legion in Morocco, Paul Dumont meets the beautiful Helene on the ship. A romance ensues, but the two decide to part when Paul learns that Helene is the fiancée of his best friend and fellow officer Raoul. Raoul is wounded during an Arab attack and the wedding is postponed, and Helene and Paul are thrown together and find it impossible to hide their feelings. The meet in the tent of Hassan, a fortune teller, not knowing the tent is a storage place for arms and ammunition belonging to Addullah, an Arab leader determined to avenge the death of his brother Ben Ali.

On the eve of his execution, a vice-rackets bigshot recalls his various exploits in crimes such as abortion and white slavery, in which he frequently operated under an alias.