Basil Rathbone character Sherlock Holmes
Nigel Bruce character Dr. John Watson
Hillary Brooke character Lydia Marlowe
Henry Daniell character Professor James Moriarty
Paul Cavanagh character Sir George Fenwick
Matthew Boulton character Inspector Gregson
Eve Amber character Maude Fenwick
Frederick Worlock character Dr. Onslow
Percival Vivian character Dr. Simnell
Coulter Irwin character Corporal Williams
Sally Shepherd character Crandon
Mary Gordon character Mrs. Hudson
John Burton character Waring the Mesmerist (uncredited)
Harold De Becker character Shoelace Vendor Henchman (uncredited)
Tony Ellis character Carter the Hypnotized Subject (uncredited)
Bess Flowers character Bar Patron (seen in mirror) (uncredited)
Kay Harding character 4th Victim (uncredited)
Alec Harford character Commissioner of the CID (uncredited)
Olaf Hytten character Fenwick's Butler Norris (uncredited)
Boyd Irwin character Short-Tempered Officer Closing Window (uncredited)
Eric Mayne character Member of Mesmer Club (uncredited)
William H. O'Brien character Pembrook House Waiter (uncredited)
