Henry Brogan, a 51-year-old former Marine Scout Sniper who works as an exceptional assassin for the Defense Intelligence Agency (DIA), is sent on a mission to assassinate an anonymous bio-terrorist aboard a train. During the mission, Henry's spotter warns him of a young girl approaching the target, causing Henry to delay his shot until the last second, shooting the man in the neck despite aiming for his head. Disillusioned with killing, Henry retires from government service.