After an absence of five years, Sophie Lang returns to the city to defend her title as its finest jewel thief. Both she and her competitor, Max Bernard, who currently uses the pseudonym of Sir Nigel Crane, lead police inspector Stone on a merry chase. Stone has never seen Sophie, despite the fact that she is often two steps away from him, and knows every move he makes because she has bugged his apartment from the apartment next door. Stone sets health-obsessed detective Stubbs to follow Bernard, hoping he will lead them to Sophie. In the meantime, Sophie has taken a personal interest in Bernard, and sets up a meeting with him by having her accomplice, Aunt Nellie, impersonate a society woman, and she her niece. The ruse works, and Sophie and Bernard are enchanted by each other. Before their date, however, they each attempt to steal a famous set of pearls at Telfen Jewelers. Augustus Telfen and Stone try to set them up by using a hidden camera and substituting fake pearls for the real ones, but Sophie foils their plans by impersonating a Russian Countess, eluding the camera's eye and stealing the real pearls. Bernard arrives at Telfen's after the theft. On their date, the thieves recognize one another for who they really are, but maintain their aliases. Bernard slyly steals the pearls from around Sophie's neck while kissing her, but he is caught by Stone in his apartment and is arrested. Sophie pretends to be shocked by her date's occupation, and under the guise of confiding in Stone, steals back the pearls. She drops them in her goldfish bowl, and after Stone realizes he has been duped, leads him on a chase through the hotel. Bernard also escapes and after tying up a Russian marshall, dons his costumes and steals his limousine. Nellie gets the pearls but the goldfish bowl becomes stuck on her hand. As Sophie joins Bernard in the limousine and they escape, Nellie smashes the bowl on Stubbs's head, and he ends up with the pearls. Sophie and Bernard, in love, set sail for England, but after Stubbs finds jewelry cleverly hidden in the plumbing of Sophie's hotel room, Stone alerts Scotland Yard of the arrival of the two thieves.