What is the title of the first Sherlock Holmes novel?

The first Sherlock Holmes novel is A Study in Scarlet.

Arthur Conan Doyle’s novel introduced both Sherlock Holmes and Dr. John Watson. It was first published in Beeton’s Christmas Annual in 1887, when Doyle was 27, and appeared in book form in July 1888 through Ward, Lock & Co. The plot begins with Watson returning from the Second Anglo-Afghan War and meeting Holmes in London.

The title comes from Holmes’s description of murder as a “study in scarlet,” comparing the bloodshed of crime with a thread running through ordinary life. A common mix-up is The Sign of the Four, which followed it in 1890 and was the second Holmes novel. The later The Hound of the Baskervilles is more famous, but it was only the third of Doyle’s four original Holmes novels.