A war hero is beaten to death for no apparent reason. The crime scene offers few clues, but Lt Joe Kenda notices an unusual pattern in the victim's head wounds and enlists a team of engineers to help him identify the murder weapon and crack the case.

When a pregnant mother and her young sons are brutally slain, pressure mounts for the CSPD to catch the monster who did it. After a city-wide manhunt, Kenda begins to tighten the noose on a prime suspect, but what happens next will shock him to his core.