How to Kill the American Witches

Susy discovers sarah's rooms empty, and is told that she left without telling anyone. Next day, susy meets up with sarah's friend, finds out about the history of witches through a professor they both know. Susy stabs marcos, though you can only see the outline of her, which causes the death of the entire cosen. And as she runs to leave the academy, the entire academy bursts into flames, and that's the end.