Burt Balaban Director, Producer Patricia Neal Susan North Actor Helmut Dantine The Stranger Actor Derek Bond Arthur Walker Actor Cyril Luckham Dr. Meinard Actor Willoughby Gray Tom Harding Actor Marigold Russell Gretchen Harding Actor Arthur Young Scientist Actor Kenneth Edwards Charles Dixon Actor David Garth First Police Officer Actor Nigel Green Second Police Officer Actor Stanley Van Beers General Actor Graham Stuart Police Chief Richards Actor John Le Mesurier Man at Desk Actor Hans Jacoby Screenwriter Gene Martel Producer Kenneth Talbot Cinematographer Peter Hunt Film Editing Eric Spear Original Music John Elphick Art Director