Sherlock Holmes’ problem with disturbing dreams proves to be both an impediment and an aid in the search for a missing woman.

Sherlock Holmes (Jeremy Brett) devises a cunning plan to snare a ruthless blackmailer who’s been causing misery throughout London. And this time, even his loyal sidekick Dr. Watson finds the Baker Street sleuth’s campaign a little strange. Based on Arthur Conan Doyle’s characters, this film features a softened version of Holmes who — zounds! — falls in love.

Mary Morstan has received a pearl in the post every year since her father’s disappearance; this leads Holmes and Watson to the truth about a secret pact between four convicts during the Indian Rebellion of 1857.