Bangkok Dangerous(2001)

Kong, a professional killer, has been mute since childhood. He works the city's toughest streets, silence his only response to the killings he performs. He is numb, acting with a sociopathic coldness as he brings down his steady, impersonal revenge on the world. Ultimately, the chance for his transformation (and redemption) arrives in the form of shop assistant Fon. She is able to provide the only tenderness and warmth he's ever known. Suddenly stricken with remorse and guilt for his past actions, he fights back against those who would force him to remain a killing machine.