Help me find this sci-fi thriller

The book was about a little girl who was sleep in a coma but had a heavy face disconformation. The world was changing. The humans as we know and seen them was evolving into the type of person they were on the inside. There was good and evil. The good were living underground and protecting the little girl. One day her face cracked open to reveal an angel.

That's all I know. It was a apocalyptic type of setting.