- Marjorie Fielding - Michael's Mother
- Herbert Lomas - George Jackson
- Geoffrey Denton - Fisher
- Cyril Chamberlain - Inspector Carter
- Hal Osmond - Agent Lawson
- Caven Watson - Dr. Ferguson
- Marianne Stone - Maisie
- Stanley Maxted - Prof. Adams
- Hartley Power - General Adams (uncredited)
- Philip Ray - Sentry (uncredited)
- Johnnie Schofield - Jim Barnes (uncredited)
- John Warren - Ted (uncredited)
- Anthony Asquith
- John Pudney
- Earl St. John
- Gordon K. McCallum
Capítulo disponible en las siguientes plataformas: