A lack of morally complex characters facing tough ethical choices makes this fast-paced thriller a lesser effort for Edgar finalist Koryta (The Prophet). At an abandoned quarry in Indiana, 13-year-old Jace Wilson, who-s just jumped into the quarry-s pool, sees two men in police uniform cut a man-s throat and toss him into the water. The killers chase Jace after finding his clothes, but he manages to escape. Jamie Bennett, a former U.S. Marshal, places Jace in the care of a friend of hers, survival trainer Ethan Serbin, who takes him along on a wilderness training program that he runs for troubled youths in Montana, though Ethan doesn-t know which of the seven boys he-ll be instructing needs witness protection. Inevitably, the two creepy killers get on Ethan-s trail. For someone as smart as Ethan is supposed to be, he fails to anticipate an obvious move on the part of the killers, leading to the first of several developments that many readers will view as contrived. Agent: David Hale Smith, Inkwell Management. (June)