John Gregson
— Inspector Parnell
Alec Clunes
— Anthony Chester
Robert Shaw
— Marlowe
Helen Cherry
— Robbie
Betty McDowall
— Maggie Parnell
William Hartnell
— Freddie Maddox
Harry Fowler
— Smiley
Alan Wheatley
— Assistant Commissioner Bewley
Kenneth Cope
— Sergeant Grey
Ernest Clark
— Police Doctor
Noel Howlett
— Brain Specialist
Renée Houston
— Masie Maddox
Piers Bishop
— Jonathan Chester
Frank Hawkins
— Mr. Tamplin
Ray Smith
— Mr. Briggs
Christopher Ellis
— Christopher Parnell
John Dunbar
— Sgt. Henry
Edward Rees
— Desk Sergeant
Robert Hunter
— Desk Sergeant
Anthony Ashdown
— Constable Jackson
Alan Curtis
— Inspector