The innocent / David Baldacci.

America has enemies--ruthless people that the police, the FBI, even the military can't stop. That's when the U.S. government calls on Will Robie, a stone-cold hit man who never questions orders and always nails his target. But Will Robie may have just made the first--and the last--mistake of his career... It begins with a hit gone wrong. Robie is dispatched to eliminate a target, but something about this mission doesn't seem right, and he does the unthinkable: he refuses to kill. Now, Robie becomes a target himself and must escape from his own people. Fleeing the scene, Robie crosses paths with a fourteen-year-old runaway whose parents were murdered, and her own life is in danger. Going against all of his professional habits, Robie rescues the girl and finds he can't walk away. He needs to help her. The more Robie learns about the girl, the more he's convinced she is at the center of a vast cover-up, one that may explain her parents' deaths and stretch to unimaginable levels of power. Now, Robie may have to step out of the shadows in order to save this girl's life ... and perhaps his own.