Jackson Valentine, known as "The Silent Killer," is a feared contract assassin who lives by a strict moral code, keeping his dark profession hidden from his beloved daughter, Emily. His final mission shakes him to his core when he''''s ordered to kill a nine-year-old boy, Devon Harper, who witnessed a crime. Unable to murder an innocent child, Jackson arranges for him to be hidden safely. He then retires from the underworld, dedicating himself to raising Emily in a quiet suburb, always fearing his past might catch up with them.