The first act of the novel introduces Calvin Dexter, the main character of the story. Dexter is described as a lawyer in his early fifties with a passion for running triathlons to keep in shape. The book digs into his past and reveals that he is a highly decorated Vietnam War veteran, and that his last tour of duty was as a tunnel rat, an extremely élite and secret task force that descended deep into the catacombs of Vietcong tunnels to hunt down the enemy in their own lairs. Dexter later married and had a daughter who at the age of 16 was lured away and forced into prostitution by Latino gang members and eventually murdered. Dexter hunts down his daughter's killers in Panama and executes them, then returns home only to discover that his beloved wife couldn't deal with the death of their only child and has committed suicide during his absence. He moves away and becomes only a small-town lawyer in his public face. But when the reason and price are right, he transforms himself into the "Avenger" and delivers justice not by killing criminals but by 'rendering' them to the United States, so that they will stand trial for their crimes against Americans. Intertwined into the backstory of Calvin Dexter is the narrative of a young American volunteer from a very privileged family who was killed while delivering aid in Bosnia during the Bosnian War.