Quick recap
Holmes's last novel is in two parts. In the first, a coded message from a Moriarty informant sends Holmes and Watson to Birlstone, where the master of a country house has been killed and the clues don't add up. In the second part, the story goes back in time to an American mining valley, where a secret society ruled the region and an undercover detective tried to bring it down. The two threads meet at the end. Published in 1915.

