Stephen Boyd as Peter Jongman

Dolores Hart as Lisa Held

Leo McKern as Brandt

Hugh Griffith as Van der Pink

Donald Pleasence as Wolters

Harry Andrews as Ayoob

Robert Stephens as Dickens

Marius Goring as Thorens

Finlay Currie as De Kool

Geoffrey Keen as Bartels

Neil McCallum as Browne

Jean Anderson as Mrs. Jongman

Jane Jordan Rogers as Anaka Jongman

Jack Gwillim as Inspector Cobb

Arthur Gross as Railway Conductor

Anne Dickins as Rachel

Vi Stevens as Barge Woman

Derek Francis as Detective Inspector

Victor Brooks as Sergeant Groninger

Geoffrey Frederick as Soldier

Clifford Elkin as Signaller