The Diamond Wizard

Dennis O'Keefe

— Joe Dennison

Margaret Sheridan

— Marline Miller

Philip Friend

— Insp. McClaren

Alan Wheatley

— Thompson Blake

Francis de Wolff

— Yeo

Eric Berry

— Hunziger

Gudrun Ure

— Sgt. Smith

Seymour Green

— Lascelles

Paul Hardtmuth

— Dr. Eric Miller

Colin Tapley

— Sir Stafford Beach

Michael Balfour

— Hoxie

Cyril Chamberlain

— Castle

Paul Carpenter

— Mickey Sweeney (uncredited)