Singing sailor Hannes, who now entertains the crowd at St. Pauli's Hippodrome after years at sea, promises his dying brother that he will take care of his ex-girlfriend Gisa. Taking Gisa to Hamburg to live with him, Hannes quickly falls in love with her, but soon has to face Gisa's affection for another man, Willem.

Sherlock Holmes and Dr. Watson embark on a search for Cleopatra's ancient necklace, which has been stolen.