Cesar Romero
— Philip 'Phil' O'Dell
Bernadette O'Farrell
— Heather McMara
Lois Maxwell
— Margaret 'Peggy' Maybrick
Geoffrey Keen
— Christopher Hampden
Campbell Singer
— Inspector Rigby
Alastair Hunter
— Det. Sgt. Reilly
Mary Mackenzie
— Marilyn Durant
Lloyd Lamble
— Martin Sorrowby
Frank Birch
— Boswell - Airport Manager
Wensley Pithey
— Sid - Bartender
Reed De Rouen
— Connors
Peter Swanwick
— Smithers
Richard Johnson
— Danny McMara - Hit-and-Run Victim
Bill Fraser
— Sales Manager
Lisa Lee
— Donna Devore
Lionel Harris
— Allan Mellon
Betty Cooper
— Dr. Campbell - Asylum Superintendent
Clare James
— Miss Andrews - Asylum Receptionist
Katie Johnson
— Mad Mary - Old Inmate at Murder Scene
Jacques Cey
— Head Waiter
Jean Bayless
— Delmont Switchboard Operator (as Jean Bayliss)
Stuart Nichol
— Steve
Marguerite Brennan
— Desk Clerk at Heather's Apartment
Robert Adair
— John - Film Director
Terry Carney
— Minor Role (uncredited)
Robert Dorning
— Airline Reservations Clerk (uncredited)
Josephine Douglas
— Nurse at Glenhaven Sanatorium (uncredited)
Christina Forrest
— Minor Role (uncredited)
Jack Howarth
— Minor Role (uncredited)
Robert Moore
— Minor Role (uncredited)