It was about a little boy named Adam.
It starts when he is born and there was something wrong with him. I think it goes about 5 years later and he doesn't talk.
People start dying (a kid, the grandfather) and Adam is always around so they think he might be killing them.
Later in the movie the actual killer tries to kill Adam's mother in the attic, Adam finally talks (yells mommy) and shoots him/kills him.
At the end of the move Adam is playing with another boy and the kid picks up a stick and tells Adam to pick up a stick and play swords, Adam picks up a bent stick and says Bang You're Dead.