Her house was burnt down, and no one knows how it started, but the police are sure someone else started it.
As a result, she didn't die, but parts of her memories were lost. Her left arm is broken, and her ankle needs time to heal, but she refuses to stay in the hospital.
Her family is fine, with only minor injuries, but she barely remembers them. While in the hospital, her friends are worried, but when she goes back to school, she has no idea who they are.
It's dangerous for her now, because anyone could tell her they were her friend, or make it clear to her that they're her foe. Even worse, someone could try to hurt her and her family, again.