The lost Shooting Star

Mabel Pines is lost, she got lost in the woods in the middle of night.
She then accidentally bumps into Bill, while she was lost.
He says he can help her for a price.
She doesn't know what to do, but shake his hand in return for his price.
He gets her safely back home, but what will he do to her now.
Her dreams are then turned into nightmares, it wasn't Bill, but someone else.
Who is this silhouette? In the shadows of death? Was it a demon? Or something else?
Bill will have to find a way to get her back, or will she die from her faith that is planned?

All will be revealed, if you can find the answer to the question....