Under her Galbraith pseudonym, J.K. Rowling impressively sustains suspense over the course of a lengthy mystery in her fourth outing for London PI Cormoran Strike and his partner, Robin Ellacott. The pair have reunited professionally after the events of 2015's Career of Evil, in which Strike fired Robin for her handling of the Shacklewell Ripper case; their personal relationship remains unsettled in the wake of Robin's marriage to a man who resents her job. The "curious case of a government minister, slashed horses and a body buried in a pink blanket, down in a dell" begins when a man named Billy, "one of those ill and desperate people you saw in the capital who were always somebody else's problem," bursts into Strike's office and claims that he saw a child strangled when he was very young. Billy flees before offering more information, but Strike's curiosity about the possible cold case leads him to try to trace Billy. Soon after, in what seems to be suspicious timing, Strike is retained by Culture Minister Jasper Chiswell to protect him against an extortionist, who turns out to be Billy's brother, Jimmy Knight. Rowling's emotionally intelligent portrayal of her protagonists never overwhelms the whodunit story line. Agent: Neil Blair, the Blair Partnership (U.K.). (Sept.)