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.
Basil Rathbone
as Sherlock Holmes
Nigel Bruce
as Dr. John H. Watson
Alan Mowbray
as Major Duncan-Bleek
Dennis Hoey
as Inspector Lestrade
Renee Godfrey
as Vivian Vedder
Frederick Worlock
as Prof. William Kilbane
Mary Forbes
as Lady Margaret Carstairs
Skelton Knaggs
as Sands - Moran's Accomplice
Billy Bevan
as Conductor Taking Tickets
Geoffrey Steele
as Roland Carstairs
Janet Murdoch
as Mrs. Shallcross (uncredited)
Gerald Hamer
as Alf Shallcross (uncredited)
