Terror by Night

Terror by Night is a 1946 Sherlock Holmes crime drama directed by Roy William Neill and starring Basil Rathbone and Nigel Bruce. The story revolves around the theft of a famous diamond aboard a train.

The film's plot is a mostly original story not directly based on any of Arthur Conan Doyle's Holmes tales, but it uses minor plot elements of "The Adventure of the Blue Carbuncle," "The Adventure of the Empty House," "The Disappearance of Lady Frances Carfax," and The Sign of Four.

In London, Vivian Vedder verifies that a carpenter has completed a coffin for her recently deceased mother's body, which she is transporting to Scotland by train. She boards the train that evening, as do Lady Margaret Carstairs, who owns and is transporting the famous Star of Rhodesia diamond; Lady Margaret's son, Roland; Sherlock Holmes, whom Roland has hired to protect the diamond; Inspector Lestrade, who is also worried about the diamond's safety; and Dr. Watson and Watson's friend Major Duncan-Bleek. Holmes briefly examines the diamond.

Shortly afterward, Roland is murdered and the diamond is allegedly stolen...