Edge by Jeffery Deaver

Corte, a professional “protector” for a secret government agency, is trained to safeguard witnesses and targets from ruthless killers. But when he’s assigned to protect a Washington, D.C. social worker and her family, he finds himself locked in a deadly psychological duel with a man known only as Henry Loving — an expert in “extraction,” whose methods are as patient as they are brutal. In a tense game of deception and survival, every move draws Corte closer to a truth that could cost him everything — and everyone he’s sworn to protect.