This Conan Doyle story has a big plus for a movie adaptation: the story takes place on a train.
Holmes has been asked to protect a famous jewel, the Star of Rhodesia, while the owner, Lady Margaret Carstairs, takes the train from London to Edinburgh. Of course Holmes cannot prevent the theft, nor is the thief (and murderer) able to get off the train. This is why train stories are among the best settings for a whodunnit: all the suspects are in their own compartments, noone can get off the train and, unlike a whodunnit in a closed room, the detective has more freedom to interrogate the suspects one by one. Of course, the whodunnits on train trips bring their own set of cliches: you can bet that someone will try and kill the detective by pushing him or her out of the train. Sadly Terror By Night isn't without those clichés and, what's worse, gives Nigel Bruce (as Holmes's sidekick Watson) too many chances to spoil the movie by cracking unfunny jokes.
Terror By Night only lasts 60 minutes, so the pace is fast enough to keep the viewer interested and the movie entertaining. The movie is in the skilled directing hands of Roy William Neill, who shot this film shortly before he died of a heart attack. Neill directed more than 100 films between 1917 and 1946, of which ten Sherlock Holmes films and movies with intriguing titles as Frankenstein Meets The Wolf Man (1943) and The Good Bad Girl. Apart from helming two Holmes films (this one and Dressed To Kill) he also directed the much praised film noir Black Angel (starring Peter Lorre) in the last year he lived. At least Roy William Neill left the planet in glory, a worthy end of a man who was born on a ship off the coasts of Ireland.