Ex-FBI agent Brigid Quinn has seen more than her share of psychopaths. She is ready to put all that behind her, building a new life in Tucson with a husband, friends, and some nice quiet work as a private investigator. Sure, she could still kill a man half her age, but she now gets her martial arts practice by teaching self-defense at a women's shelter.

But sometimes it isn't that simple. When her sister-in-law dies, Brigid take in her seventeen-year-old niece, Gemma Kate. There has always been something unsettling about Gemma-Kate, but family is family. Which is fine, until Gemma-Kate starts taking an unhealthy interest in dissecting the local wildlife.

Meanwhile, Brigid agrees to help a local couple by investigating the death of their son—which also turns out not to be that simple. Her house isn't the sanctuary it used to be, and new dangers—including murder—seem to lurk everywhere. Brigid starts to wonder if there is anyone she can trust, or if the devil has simply moved closer to home.