This book is absolutely amazing. It's full of gore, creepiness and mystery. The Hollow sisters are shrouded in mystery from the get go. They disappeared as children for a month and no one knows where they were, not even themselves. We spend the entirety of the story trying to figure out where the little girls were and what happened to them. Let me tell you, even the best of sleuths will never guess this creepy ending. I love that YA is branching out to darker Gorey(er) things. The Hollow sister are alluring and seeping with charisma and power. Until a sister goes missing, they go looking and open a door to a place they shouldn't have. Creepy, supernatural things start following them. Things that seem to have came from where they disappeared to years prior. The girls begin to realize that the so called harmless place they disappeared to years ago might not be so harmless after all.