Paul Temple is on the trail of a gang of international criminals trying to steal atomic secrets.

John Bentley as Paul Temple
Dinah Sheridan as Steve Temple
Barbara Couper as Mrs. Morgan
Hugh Dempster as Oliver Ffollett
Dino Galvani as Van Draper
Andrew Leigh as Professor Hardwick
Anne Hayes as Celia Hardwick
Jack Livesey as Sir Graham Forbes
Jenny Mathot as Jacqueline Giraud
Ivan Samson as Major Murray
Bruce Seton as Bill Bryant
Beatrice Varley as Mrs. Weston
Peter Butterworth as Telephone Engineer
Shaym Bahadur as Rikki