Gemini Man
Henry Brogan, an aging former Marine Scout Sniper who now works as an assassin for the Defense Intelligence Agency (DIA), is sent on a mission to assassinate an anonymous terrorist aboard a bullet 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.