The Fatal Hour.

A young woman (Linda Arvidson) is kidnapped by a band of opportunistic Chinese slavers, led by devious Pong Lee (Harry Solter). A resourceful female police operative (Marion Leonard) is determined to rescue her, and tracks the mastermind of the kidnap plot, Hendricks (George Gebhardt). Though successful in her rescue effort, the rescuer ends up being made a prisoner herself. The slavers plan to make her the victim of a pistol shot to be triggered by the hands of a clock. The heroine is rescued by police seconds before the hands of the clock reach the "fatal hour".