A privileged gentleman hires Holmes to accompany him and his mother aboard a train traveling from London to Edinburgh, where they will be safeguarding the Star of Rhodesia, an exceptionally large diamond. Joining them are Dr. Watson and Insp. Lestrade, who claims to be fishing but clearly isn’t. What follows is a perilous journey filled with misleading clues, including stolen teapots and a coffin, before it becomes clear that the notorious Col. Moran is also on board and determined to steal the gem. The story moves swiftly, developing effectively toward an unusual ending punctuated by several close calls. It's an enjoyable way to pass sixty minutes.

Source on TMDB