What is the name of the Holmes story in which the detective disguises himself as a bookseller to catch a criminal?

The Adventure of the Empty House is the Holmes story in which the detective disguises himself as a bookseller to catch a criminal.

Arthur Conan Doyle published the story in 1903 after bringing Holmes back from his apparent death at Reichenbach Falls. Holmes uses the disguise while investigating Colonel Sebastian Moran, the former army officer and dangerous criminal associated with Professor Moriarty’s network.

The disguise helps Holmes observe Moran without immediately revealing that he has survived. The story also explains how Holmes escaped the confrontation at the falls, using his knowledge of climbing and the surrounding terrain.

The Empty House was a major event in the canon because it ended the famous “Great Hiatus.” Watson believes Holmes dead until the detective suddenly appears in Baker Street. The disguise is one of several methods Holmes uses to gather evidence before confronting Moran.