Nancy is a teen that found a door in her cellar that lead to the Halls of the Dead. She was there until the Lord of the Dead told her she had to return to the world of the living until she was sure. Her parents were quite upset that she wasn't the girl they remembered so they sent her to Eleanor West's Home for Wayward Children in the hope they could get her back. What they didn't know is that Eleanor West's Home is a boarding school for the children who wandered into portal worlds and want to go back to those worlds.
This is an interesting little story set in an intriguing world. The plot is the weakest part of the story, basically a series of murders that drive the character interactions. The characters, on the other hand, are interesting and complicated. Each one reflects the world they travelled to. The interactions between the characters are enjoyable. The universe is also quite complicated with each portal world classified on several dimensions. The main two are Nonsense/Logic and Virtue/Wicked. As mentioned all of the students want to return to their world, which adds an interesting tension to the conversations since they all know how unlikely it is they can return.
Overall I do recommend reading it. Just bear in mind that it isn't your usual fantasy novel.