- Eric Pohlmann - Commissionner Aristide Goron
- Eric Pohlmann - Goron
- Eric Pohlmann - The Emir
- Patrick Barr - Horton
- Russell Waters - Hocksby
- Alan Wheatley - O'Brien
- Olaf Pooley - Carlmeddy
- Hubert Gregg - Pennacott
- Rosalie Crutchley - Annette
- Richard O'Sullivan - Roger
- Eliot Makeham - 1st Judge
- Mary Clare - Mrs. Wrigley
- Zena Marshall - Madeleine
- John Schlesinger - Dutch Cook
- Patricia Owens - Betty Hartley
- George Coulouris - Harwood
- John Hewer - John Parrish
- Elspet Gray - Johanna
- Anthony Newley - Ned
- Glyn Houston - Peter Ridgway
- Christopher Lee - Jeanpierre
- Rachel Gurney - Martha
- Tony Wright - Terry Fortescue / Henry Fortescue
- Richard Wattis - Arthur Cabot
- Peter Dyneley - Red Darrow
- Laurence Payne - Delius
- Lionel Murton - Crowder
- Alec Mango - Narbu
- Michael Shepley - Sir Nigel
- Phil Brown - Gordon
- Phil Brown - Dr. Bryan Hayes
- Marne Maitland - Thoreau
- Marne Maitland - Waiter
- Nora Gordon - Housekeeper
- Peter Illing - Lavois
- Joan Sims - Marjorie Dawson
- Tommy Duggan - Lawton
- John Laurie - Dr. Brandeis
- Dana Wynter - Francine Rapport
- John Arnatt - Wesley
- Hugh Griffith - Dr. Ivy
- Adrienne Corri - Clara
- Patrick Holt - Paul
- Doris Hare - Lydia
- Rachel Kempson - Helen Rune
- Arthur Hill - Jerry
- Bruce Seton - Capt. Hartnett (uncredited)
- Robert Brown - Hastings
- Sheila Burrell - Joan Forsythe
- Robert Ayres - Wyatt
- Sandra Dorne - Rosie
- Alfred Burke - Minister
- Anton Diffring - Francois
- Anton Diffring - Davos
- Ronald Leigh-Hunt - Ireton Boulder
- Eugene Deckers - Phillipe
- Patricia Laffan - Jane
- Hugh Williams - Harold Hartley
- Patricia Marmont - Marion
- Martin Benson - Dupont
- Peter Asher - Andrew
- Michael Alexander - Dr. Walker
- Hannah Weinstein
- Edwin Astley
John Laurie interpreta a Dr. Brandeis en la serie.
Christopher Lee hace el papel de Jeanpierre.
Adrienne Corri hace el papel de Clara.
Boris Karloff interpreta a Colonel March Of Scotland Yard en la serie.
Ewan Roberts hace el papel de Inspector Ames.
Eric Pohlmann interpreta a Commissionner Aristide Goron en la serie.
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