What is the title of the first Sherlock Holmes book by Arthur Conan Doyle?

The story behind the answer

A Study in Scarlet is the first Sherlock Holmes novel, published in 1887 in Beeton’s Christmas Annual. It introduces both Sherlock Holmes and Dr. John Watson, narrates their first meeting, and establishes 221B Baker Street and Holmes’s method of deduction. By contrast, The Sign of the Four is the second Holmes novel (1890), A Case of Identity is a later short story, and The Doings of Raffles Haw is a non-Holmes novel by Conan Doyle.

The title comes from Holmes’s line about tracing “the scarlet thread of murder” through the colorless skein of life. Unusually, the book shifts midway to a Western backstory in Utah, showing Doyle’s flair for mixing genres. Memory tip