Baroness Teri von Horhenfels [Kay Francis] is a Viennese aristocrat who grows tired of the luxury and boredom of life with her rich but dull husband Baron Franz Hohenfels [Henry Kolker], turning to flirtations and secret adventures to keep her days interesting. One day, inside an exclusive jewel shop where the Baron is supposed to buy her a dazzling 28-carat diamond ring, she crosses paths with a suave jewel thief [William Powell] and his gang, whose charm and audacity pull her into a world she’s never fully dared to explore. The thief is enchanted by her bold, carefree spirit and, in a bold gambit, he locks the Baron and her current lover, Paul [Hardie Albright], a young cabinet minister she has already tired of, in a vault and forces Hollander [Lee Kohlmar], the shop owner, to smoke a marijuana-laced cigarette that sends him into a fog of forgetfulness. Yet Teri, wary of danger but curious about this rogue’s allure, manages to persuade him to let her go, even as he takes her ring as a keepsake of the night.
After misdirecting the police, Teri returns home, and she finds herself envied by her equally bored but less reckless friend Marianne [Helen Vinson], who reads the rumor mill with keen interest. A vase of flowers appears at the house, and the housekeeper notes no delivery was made, leading Teri to suspect the thief has already visited. She and Marianne ascend to her suite to discover that the safe has been cracked, yet nothing seems stolen and Teri’s ring is mysteriously returned. Marianne, sensing looming scandal, departs quickly to avoid trouble, while Teri faces the strange calm of the evening and the memory of the night’s events.
The thief then reappears through the window, revealing that the diamonds taken from the jewel shop are hidden inside the safe and explaining that it is the safest place to hide them. Teri, anxious about being branded an accomplice if she ever returns the ring, tries to persuade him to take back the ring, but he refuses and hints at using her as a pawn in his larger game. In the midst of this, Detective Fritz [Alan Mowbray] arrives, seemingly to flush out the robber, and takes the two into custody. Yet the arrest is a staged ruse—Fritz is in fact part of the gang, and the ruse has been used to transport Teri to the thief’s home for a night of romance.
Teri is intrigued, but she resists a full surrender to passion, demanding that she be wooed rather than simply used. He opens his world of safes and past heists, a glamorous yet dangerous gallery that Vienna has already made too hot to handle. He suggests meeting again in Nice, but just as the plan forms, the real police storm the place. In a desperate ploy, he ties Teri up to divert suspicion, then flees as the room erupts in chaos. Pretending fear, she calls for help, and after she is untied, she offers a feigned description of the thief. With the night’s adrenaline still coursing through her veins, she declares that she needs a vacation to recover from all the excitement and announces plans to catch the first train to Nice, leaving the door open for another adventure—and, in a final playful wink, she looks directly toward the camera.
