Basil Rathbone
Sherlock Holmes

Nigel Bruce
Doctor Watson

Evelyn Ankers
Kitty

Reginald Denny
Sir Evan Barham

Thomas Gomez
R.F. Meade

Henry Daniell
Sir Anthony Lloyd

Montagu Love
General Jerome Lawford

Olaf Hytten
Admiral Sir John Fabian Prentiss

Leyland Hodgson
Captain Roland Shore

Mary Gordon
Mrs. Hudson

Hillary Brooke
Jill Grandis

Harry Cording
Camberwell

Herbert Evans
Smithson - Barham's Butler (uncredited)

Fred Graham
Meade's Henchman (uncredited)

Gavin Muir
BBC Radio Announcer (voice) (uncredited)

Edgar Barrier
Voice of Terror (voice) (uncredited)