Yes, I’ve conflated the titles of two Sherlock Holmes novellas here (“conflated” – did I really write that word?).
I confess to not having read The Valley of Fear for a long time, and it’s been some time since I read A Study in Scarlet. There are some real similarities, though. Both involve a murder of a particularly unusual kind, and both involve a flashback sequence to an American past.
What is really striking about the central portion of both books is the attitude of Conan Doyle to American society.