Deputy U.S. Marshal Frank Bass faces his most challenging and disturbing case when an old friend, the Chief of Police in Austin, Texas wires to ask for help. A serial killer is at large in the city terrorizing the populace with grisly murders committed only on the first of each month. His gruesome tactics earn him the name Annihilator, and he perpetrates his ghastly atrocities only on young female victims. He is as clever as he is mad and revels in bedevilling authorities with cunning misdirection and aliases, taunting them in his joyous insanity. Bass's investigation is taken from one eerie locale to another in his effort to hunt down the most heinous fiend in the analogues of Texas crime. Along the way Bass establishes new kinships and re-establishes an old one, a Pinkerton Detective from a previous case in Texas where he was disguised as an itinerant prospector known as Heeltap. In metropolitan Austin, Bass is exposed to police procedures and new techniques which are worlds apart from his own area of expertise, law enforcement on the frontier. This story is based on true accounts of the man author O. Henry dubbed the Servant Girl Annihilator. His crimes against humanity have never been resolved.