Forty years after he stumbles upon the horrific mutilation of a team of U.S. Rangers in Vietnam, Seth O'Malley wanders into a cat-and-mouse game with a mutilating psychopath. After murdering and mutilating some of the best detectives in the country, the psychopath is looking to mutilate the big prize—Seth O'Malley.

As Ava and her team investigate the unusual markings on the remains of immigrants found dead in the deserts of Arizona, Seth travels Colorado investigating cattle mutilation until an old friend points him in the right direction. In a race against time, Seth must keep his friend and housekeeper, Maresol, from being the next victim, and in the process he must confront a demon from his past.

The Carving Knife is fast ride through the Colorado landscape of UFOs, cattle mutilation, and demons to catch the real psychopath behind the blade.