Susan Strasberg as Penny Appleby

Ronald Lewis as Robert

Ann Todd as Jane Appleby

Christopher Lee as Doctor Pierre Gerrard

John Serret as Inspector Legrand

Leonard Sachs as Mr. Spratt

Anne Blake as Marie the Maid

Fred Johnson as Father

Madame Lobegue as Swiss Air Hostess (uncredited)

Bernard Browne as Gendarme (uncredited)

Frederick Rawlings as Plainclothes Sergeant (uncredited)

Richard Klee as Plainclothes Sergeant (uncredited)

Brian Jackson as Plainclothes Officer (uncredited)

Heinz Bernard as Plainclothes Officer (uncredited)

Frederick Schrecker as Plainclothes Officer (uncredited)

Gordon Sterne as Policeman (uncredited)

Rodney Burke as Policeman (uncredited)