This is the third Jack Keller book, and each one has edged farther away from the "crime" category and into the "thriller" area. Don't ask me to explain the difference. I know it when I read it.
The title doesn't really apply to anybody in the book as far as I can tell. Nobody's safe, and nobody's sound, least of all Keller. You really need to have read the first two books in the series to know about Keller, the problems he's had in the past, if you want to understand what's happening, but here's the short version. He had a particularly bad experience in Afghanistan, but he's been slowly getting better. Unfortunately, he keeps finding himself in situations where he has to let the violence inside him escape. He tries to keep it tamped down, but he keeps finding himself in situations where he has to use it to save himself or someone he loves. And once it gets out, there's no controlling it.
This time there's a kidnapping, two of them, really, and the man behind them is bad. Awfully bad. A torturer. He's after the mcguffin, which is something I won't tell you about, since Rhoades keeps it a secret for a while. If he can, I can, and it doesn't matter, anyhow. It's just the thing that sets off the action, of which there's plenty. The book never slows down. Don't expect a happy ending. Anyone can die at any time, and some wounds aren't caused by guns and knives. Check it out.