Pulled off the hunt for Anson Bishop by the feds, Detective Sam Porter and the Chicago Metro team catch a case that should not be possible: the body of Ella Reynolds, missing three weeks, is found beneath the ice of Jackson Park Lagoon — a lagoon that froze months before she disappeared. Stranger still, she is wearing the clothes of another girl who has been gone less than two days.
While Clair Norton and Nash work the developing case, Porter cannot let the Four Monkey Killer go. Convinced that the way to find Bishop is to find his mother, he follows a single grainy photograph out of Chicago and into New Orleans, and into a past far darker than he expected — where he comes to understand that the only thing more frightening than the mind of a serial killer is the mind of the mother who made him. When the captain learns what he has been doing, Porter is suspended, and his partners are left to chase the new killer alone.
J. D. Barker's sequel to The Fourth Monkey braids its threads together in short, switching chapters — Porter's obsession, Clair's investigation, and the account of a girl already in the killer's hands — and tightens them toward a cliffhanger that sets up the rest of the trilogy. Published by Houghton Mifflin Harcourt in July 2018.