Bestseller Brennan's workmanlike 15th mystery featuring FBI agent Lucy Kincaid (after 2018's Too Far Gone) teams Lucy, who has been with the bureau for less than two years, with Jerry Walker, a veteran San Antonio, Tex., sheriff's deputy, on a particularly baffling serial killer case. The murderer's most recent victim, chef Julio Garcia, was beaten before being shot in the face. The location of the gunshot wound, and the details of the beatings—Garcia's hands were smashed, and he was hit in the stomach and groin—match those of the two previous victims. Walker, who harbors a deep resentment toward the FBI based on a botched kidnapping case 10 years earlier, denigrates Lucy's limited experience, and is skeptical that profiling will be of any use in the investigation. Predictably, the professional relationship thaws as Lucy proves her worth, and the pair interview the dead men's survivors in an effort to find any possible motive connecting the killings. Though nothing distinguishes the leads from similar characters in other comparable whodunits, a clever twist on a classic golden-age plot device more than compensates. Agent: Dan Conaway, Writers House. (Apr.)