In a Hong Kong park, a man brushes against the arm of a girl sitting on a bench, and she slips to the ground, murdered. Immediately afterward, the man is kiled also. The F.B.I.(say what?) swings into action: the dead woman was connected with a jewel-smuggling ring, and the man was a federal agent.Federal agent Scott (Stewart Granger) is given the assignment and finds a way to sneak agent Carol (Rosanna Schiaffino) into the smuggling gang, and then contacts Norman (Paul Kronak), the F.B.I connection in Hong Kong. Carol is working now for Pierre Milot (Sieghardt Rupp), the man who directs the underground traffic for an unknown mysterious boss. Well, make that unknown to all but members of the audience who are not deaf, blind or have fallen asleep.

An FBI agent and a woman involved in a smuggling racket are both murdered in Hong Kong, and another FBI agent, Michael Scott, is called in to investigate. Carol, assigned to assist Scott, is placed as a telegraphist in an organization suspected of conducting the smuggling operation. She is supervised by Pierre Milot and his mistress, Blanche, but the identity of the mastermind behind the combine remains a mystery. Scott contacts the regular Hong Kong FBI agent, Norman, who keeps in touch with both Scott and Carol by means of transmitters concealed in their wristwatches. Later Blanche discovers Carol trying to steal Milot's code book and subjects her to torture. Scott, meanwhile, has learned that river junks are being used to smuggle gems and electrical equipment to mainland China. After several attempts have been made upon his life, he suddenly finds himself face to face with the mysterious gang leader, who is revealed to be Norman. In a climactic fight aboard one of the junks, Scott succeeds in overpowering Norman and blowing up the boat. Satisfied with a job well done, Scott is reunited with Carol.