This novel is a bare-knuckle revenge thriller with a despicable protagonist who enacts violence on people slightly more despicable than him. Parker has just escaped from prison, where he’d been picked up as a vagrant. He wasn’t actually a vagrant but was in disguise in order to lay low after a bad job (he’s in the organized heist business). His partner and his wife betrayed him, and she shot him and left him for dead. Now back in town, he’s trying to figure out who to kill and who to get his money from.
He goes ahead and kills his wife first, as you do. We ultimately learn the situation was more complicated than it seemed, but not really to Parker, I guess.
Anyway, Parker starts figuring out what happened in the job. He was part of a crew, the cover got blown, or did seemingly, and Parker was left out to dry. We also find out that the job was part of a organized, nation-wide crew, so he’s going to be able to exactly his revenge one way or the other. When it turns out that his portion of the cut was given to the syndicate in order to pay off a debt, he figures the syndicate now owes him the money, which he tells them. They laugh, but he promises to be very difficult, and they can get rid of him by paying him off. Well, as you can imagine things go awry, and sets up for dozens of sequels as he plans of taking as much from them as he can.