The three locks

MacBird's intriguing fourth Sherlock Holmes adventure (after 2019's The Devil's Due) centers on three possibly connected mysteries. The first fleshes out the backstory of Dr. Watson, who's unsettled to receive a letter and a locked box from an unknown woman, Elspeth Carnachan, who claims to have been his late father's estranged half-sister. In the letter, Carnachan states the box was given to her by Watson's mother, who died under mysterious circumstances two days afterward. Carnachan was supposed to pass the box to Watson when he turned 21, but forgot. Meanwhile, Watson and Holmes get two more puzzles to handle. One involves a magician whose wife worries that a human finger sent to her husband presages a threat to him. Another prospective client, a deacon, worries about the disappearance of a young woman he's fond of whose family members don't appear concerned. MacBird artfully alternates among the multiple plotlines, maximizing suspense. With its deep probe into the friendship between the detective and the doctor, this is a good choice for fans of Lyndsay Faye's Sherlock Holmes pastiches. Agent: Linda Langton, Langton's International. (Apr.)