While in London trying to nab several fugitives who stole a million dollars from a U.S. Treasury vault, American federal agent Dennison (Dennis O'Keefe) assists Scotland Yard Insp. McClaren (Philip Friend) in his search for a missing atomic scientist (Paul Hardtmuth). The detective duo discovers that the key to solving both cases may rest with the scientist's daughter (Margaret Sheridan) and her fascinating diamond.
A brilliant scientist who has lost his memory is hunted by Communist agents out to obtain a secret formula.
A woman travels to England to attend her parents' funeral. She is told by officials that they died of natural causes together, but she doesn't buy it. She comes to suspect that the nurse who took care of her parents was involved in their deaths, but since the nurse is well thought of in the town, no one believes her. What she doesn't know is that her parents' killer has selected her as the next victim
A doctor becomes the victim of extortionists when one of his patients dies under questionable circumstances.
