Circle of Shadows

British author Robertson’s fourth mystery (after 2012’s Island of Bones), the best yet in her late-18th-century historical series, takes widow Harriet Westerman and her investigative partner, anatomist Gabriel Crowther, to Germany’s Duchy of Maulberg, where her brother-in-law, Daniel Clode, has been charged with murder. Clode, disoriented and bleeding from an apparent suicide attempt, was found behind a locked door near the smothered corpse of Maria Martesen, Countess of Fraken-Lichtenberg. Westerman and Crowther, having doubts about Clode’s guilt, soon find evidence suggesting someone else was the killer. The case is especially sensitive, since Maulberg is in debt to England, and Clode’s conviction and execution if they can’t clear him could plunge the duchy into financial ruin. Roberston adds in the intrigues of a secret society, the Minervals, whose scheming may have played a part in the death of the countess, among others. The puzzle is intricate enough to satisfy fair-play fans, but it’s the perfect prose that puts this in the first rank of the subgenre. Agent: Annette Green, Annette Green Agency (U.K.). (June)