Possession Story Idea

Okay, I had an idea about a possession TG story. The reason I made this thread is for ideas to help the story come along, because all I have is the basics of the beginning.

Anyways, here's the summary of the beginning:

Alex (the protagonist) has always been a loner. He doesn't keep up with trends, and doesn't care about anything popular. He would skip school, but his mother insists on giving him a good education. While going to get groceries after school one day, he get's run over by a car. He sees a flash of light, and then everything turns black. Alex feels like he's floating in the darkness, but then a light appears in the distance. He is pulled toward the light, and can't get away.

At the same time, a group of girls that have found a magic book are trying to contact an otherworldly spirit. The spirit they get in contact with is Alex. Alex is forced down into the body of one of the girls in the ceremony, who was designated as the 'possession doll'.

Unfortunately, that's about as far as I got. I'm pretty sure it'll make a good story, but I'm still having trouble thinking of the next parts. Anybody got any opinions?