Hanna is Harry Potter's twin sister. But, he doesn't know she exists, and she only know that she has a brother that may or may not be dead.
She was raised by Bobby Singer. She was raised a hunter.
So what happens when her, Sam, and Dean go to London to investigate a case that they think Crowley has something to do with, only to find a whole other world, a world of magic?
What will Hanna do when she finds the brother she thought she would never have?
What about when Sam, Dean, and Hanna are faced with the possibility that something... magic could be behind the case?
And when they find that a man that they only know by He-Who-Shall-Not-Be-Named wants to kill her, simply because of her blood relations?