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 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
Paul Maxwell plays Craig Owen, an incarcerated criminal whose cellmate holds the secret to the valuable contents within a safe deposit box. When the cellmate dies, Owen breaks out of jail in search of the stash. Unable to open the box, the fugitive abducts Linda (Felicity Young), the dead man's daughter. Tension mounts as the girl plays for time to prevent her own demise.
