A Victorian mystery that rewrites And Then There Were None with a very different ending.
Lord Hargrave hires detective Cyrus Barker and his assistant, Thomas Llewelyn, to provide security for his secret meeting with French Ambassador Michel Gascoigne to discuss a new treaty. The meeting will be disguised as a house party at Hargrave’s home on Godolphin Island in the Isles of Scilly. Barker’s cover will be provided by his lady friend, Philippa Ashleigh, a close friend of Lady Barker. The island has no telephone, only a red flag to run up a pole when help is required. Aside from the two detectives, the Hargraves, their daughter and two sons, and the ambassador, the party includes his lordship’s doctor and his two daughters; Delacroix, the ambassador’s bodyguard; the Honorable Algernon Kerry, an unpleasant old family friend recently returned from South America; Lady Alicia Travers; Colonel and Mrs. Fraser; and some 15 servants. On the first night, Hargrave is shot dead by an expert marksman, the ferry that brought the ambassador is sent away by a faked note, and Delacroix is found stabbed. Although the assassin has many opportunities to kill at will, he seems to be highly selective. A search of the island reveals only that the flag to call for help has been destroyed and the rifle used to kill Hargrave was stolen from his gun cabinet, suggesting an inside connection. Blamed for not protecting Hargrave, Barker and Llewelyn are frozen out but continue to hunt for clues to the killer. The preferred targets, members of the Hargrave family, lead Barker to suspect that the motive may be personal rather than an international conspiracy to stop the treaty.
Thomas (Anatomy of Evil, 2015, etc.) supplies plenty of suspects and red herrings, ratcheting up the tension steadily as he winnows the targets to make this period adventure one of his best.