From Constantinople to Marseilles, aboard a cargo ship, an intrigue full of adventures brings together a courageous young girl and a young risk-taker who succeeds in thwarting a series of long-planned crimes.
Viktor Schott, daredevil and womanizer, is charged by his father, a jeweler, to go to Istanbul and purchase a valuable emerald necklace from a rich Persian and to bring it back by ship to Marseille. A pair of criminals are watching him and attractive Delia, with whom Viktor is in love, is used as bait. His boyhood friend Sibyl, who is in love with Viktor, warns him of the criminal ship owner and the captain, who intend to steal the jewel during a masked ball on board. Shortly before reaching the coast of France, an explosion causes the ship to capsize.
Charley Wyckham and Jack Chesney pressure fellow student Fancourt Babberly to pose as Charley's Brazilian Aunt Donna Lucia. Their purpose is to have a chaperone for their amorous visits with Amy and Kitty, niece and ward of crusty Stephen Spettigue. Complications begin when Fancourt, in drag, becomes the love object of old Spettigue and Sir Francis Chesney.
The unemployed secretary Käte applies a job by mistake in the piano factory of the entrepreneur Helmut Hofert. He does not really have any need for an additional secretary at the moment, but Käte is very attractive.
Diplomat Fürst Windischberg is known for spending too much time with women, receiving frequent reprimands and even a threat to be sent to Afrika. In Berlin he meets chorus girl Hella, who tells her companions she is his current flirt.
