The Casebook of Sherlock Holmes, published in 1927, collects the final set of Sherlock Holmes stories authored by Arthur Conan Doyle. All of the included stories appeared previously in The Strand Magazine between October 1921 and April 1927.

As usual, the mysteries generally purport to be accounts written by Holmes’s friend Dr. John Watson. Uniquely, however, three stories in the Casebook are presented from alternative points of view: “The Adventure of the Mazarin Stone” is narrated in the third person, since it was adapted from a stage play in which Watson hardly appeared; and “The Adventure of the Blanched Soldier” and “The Adventure of the Lion’s Mane” are both narrated by Holmes himself, the latter being set after his retirement as a detective.