Leslie Howard as Professor Horatio Smith

Francis L. Sullivan as General von Graum

Mary Morris as Ludmilla Koslowski

Hugh McDermott as David Maxwell

Raymond Huntley as Marx

Manning Whiley as Bertie Gregson

Peter Gawthorne as Sidimir Koslowski

Allan Jeayes as Dr Benckendorf

Dennis Arundell as Hoffman

Joan Kemp-Welch as School-Teacher

Philip Friend as Spencer

Laurence Kitchin as Clarence Elstead

David Tomlinson as Steve

Basil Appleby as Jock MacIntyre

Percy Walsh as Dvorak

Suzanne Clair as Salesgirl

Roland Pertwee as Embassy Official - Sir George Smith

Charles Paton as Steinhof

Aubrey Mallalieu as Dean

George Street as Schmidt

Oriel Ross as Lady Willoughby

Bryan Herbert as Jaromir

Arthur Hambling as Jordan

Ben Williams as Graubitz

Ernest Butcher as Weber

Mary Brown as Girl Student

W. Phillip as Innkeeper

Ilse Bard as Gretchen

Ernest Verne as German Officer

Hector Abbas as Karl Meyer

Neal Arden as Second Prisoner

Richard George as Prison Guard

Roddy Hughes as Zigor

Hugh Pryse as Wagner

Michael Brennan as Camp Guard with Lantern

Elwyn Brook-Jones as Bit Part

Sebastian Cabot as Bit Role

Peter Cozens as Man

Arthur Denton as Gestapo Man Following Smith

Irene Handl as Bit Part

Vincent Holman as Doctor at Diggings

Ronald Howard as Minor Role

Stuart Latham as Telephone Operator

Michael Rennie as Prison Camp Officer

Charles Rolfe as German Officer at Customs

John Slater as Reporter

Harry Terry as Camp Guard

A.E. Matthews as Earl of Meadowbrook