The Adventure of the Second Stain

In Sir Arthur Conan Doyle's "The Adventure of the Second Stain," Sherlock Holmes is approached by high-level officials, including the Prime Minister, to investigate the theft of a sensitive document hidden within the Secretary of State for European Affairs's home. The case involves the mysterious disappearance of a secret letter that could have serious implications for Europe, and Holmes must uncover the truth behind its theft without knowing all the details at the outset. This story is part of the collection "The Return of Sherlock Holmes" and is noted for being one of Doyle's favored Holmes adventures.