Derek Bond as Saturday Keith

Rona Anderson as Joanna Benbow

James Robertson Justice as Prof. Benbow

John McLaren as Elmer Van Buren

Barbara Murray as Nelly Bly

Peter Croft as Quentin Cotton

Leslie Dwyer as Holly

Joyce Grenfell as Miss Horsefell-Hughes

Fabia Drake as Lady Mercy Cotton

Maurice Denham as PC Windle

Kay Cavendish as Jean Forbes

Andrew Osborn as Williams

Iris Hoey as Lady Keith