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.
Dennis O'Keefe
Joe Dennison
Margaret Sheridan
Marline Miller
Philip Friend
Insp. McClaren
Alan Wheatley
Thompson Blake
Francis de Wolff
Yeo
Eric Berry
Hunziger
Gudrun Ure
Sgt. Smith
Seymour Green
Lascelles
