Raichev's mannered sleuthing couple, Maj. Hugh Payne and his wife, mystery writer Antonia Darcy, tackle their fifth case (after 2009's The Little Victim
) in rather disappointing fashion. While dining at Claridge's in London, Captain Jesty, a regimental comrade of Payne's who's enamored of a beautiful young woman, Penelope Tradescant, observes Penelope surreptitiously switch capsules in the pill case of her much older, wealthy husband, Sir Seymour Tradescant. Within days Sir Seymour is dead in circumstances that leave many other suspects, including his twin sister, his son, and members of Mayholme Manor, a retreat where Seymour often stayed. Set in the present but written in classic British mystery style, this slight effort often refers to the dos and don'ts of mystery writing, not all of which the author follows. Providing a deus ex machina solution when Darcy says she'd never do so in her own detective novels, for example, will strike some readers as more lame than clever. (Apr.)