
Holmes and Watson board a passenger train bound from London to Edinburgh, to guard the Star of Rhodesia, an enormous diamond worth a fortune belonging to an elderly woman of wealth; but within the first hour of the trip, the woman's son is murdered and the diamond stolen and any of the passengers in their car could be the killer thief.

as Sherlock Holmes

as Dr. John H. Watson

as Major Duncan-Bleek

as Inspector Lestrade

as Vivian Vedder

as Prof. William Kilbane

as Lady Margaret Carstairs

as Sands - Moran's Accomplice

as Conductor Taking Tickets

as Roland Carstairs

as Mrs. Shallcross (uncredited)

as Alf Shallcross (uncredited)

as Senior Conductor (uncredited)

as Mock the Undertaker (uncredited)

as Baggage Car Guard (uncredited)

as "Inspector MacDonald" (uncredited)

as Mock Jr. (uncredited)

as Dining Car Steward (uncredited)

as Elderly gentleman on train station (uncredited)