Terror By Night is a 1946 Sherlock Holmes black and white movie, that stars Basil Rathbone as Holmes and Nigel Bruce as Doctor Watson.
Holmes is hired to accompany Lady Margaret and her son on a train journey to Scotland, to protect the Star of Rhodesia diamond.
There are murders, the diamond is stolen, Holmes has brought along a counterfeit copy and the drama ends with Watson’s friend being the real culprit.