The Sign of Four (1983)

Mary Morstan comes to Baker Street with a strange story: since her father vanished years ago, someone has sent her a valuable pearl every year, and now she has been summoned to a secret meeting. Holmes and Watson accompany her, and the trail leads to a murdered man, a locked room, the Agra treasure stolen during the 1857 uprising in India and a one-legged man with a terrible grudge. This British adaptation of Arthur Conan Doyle's second Holmes novel stars Ian Richardson as an elegant, quick-witted Holmes, and ends with a famous boat chase along the Thames. It was one of two Holmes films Richardson made in 1983, the other being The Hound of the Baskervilles.