The famous Borgia Pearl, a valuable gem with a history of bringing murder and misfortune to its owner since the days of the Borgias, is brought to London, thanks in part to Sherlock Holmes. But before long the jewel is stolen, due to an error on Holmes' part, and shortly thereafter, a series of horrible murders begin, the murderer leaving his victims with their spines snapped and surrounded by a mass of smashed china.

Basil Rathbone
as Sherlock Holmes

Nigel Bruce
as Dr. John Watson

Dennis Hoey
as Inspector Lestrade

Evelyn Ankers
as Naomi Drake

Miles Mander
as Giles Conover

Ian Wolfe
as Amos Hodder

Charles Francis
as Francis Digby, curator

Holmes Herbert
as James Goodram, courier

Richard Aherne
as Museum Guard Bates

Mary Gordon
as Mrs. Hudson
CinemaSerf
Having safely snaffled the blood-steeped “Borgia Pearl” from the dastardly clutches of “Giles Conover” (Miles Mander) “Holmes” (Basil Rathbone) is hoist by his own petard when his rather pompous illustration to the museum curator of the flaws of electronic security systems only sees it stolen again!...