Best friend

A young boy stands in a sunlit yard, looking startled as white particles fall around him, then the scene shifts to a dark, wooded area where he looks up in fear, followed by a girl with glasses and a backpack standing in a dimly lit tunnel, then two boys screaming in a dark room, and finally a group of children in a cluttered, dimly lit room where one boy is being held down by others while a girl stands over them.