Force of Nature (en Inglés) - C. J. Box

In 1995, Nate was in a secret Special Forces unit abroad when a colleague did something terrible. Now high up in the government, the man is determined to eliminate anyone who knows about it, and Nate knows exactly how he'll do it-by striking at Nate's friends to draw him out. The entire Pickett family will be a target, and the only way to fight back is outside the law. Nate knows he can do it, but he isn't sure about his straight-arrow friend-and all their lives could depend on it.