From the Bookshelf of University of Cambridge, Faculty of Education, Primary PGCE 2019-20 …

[close] A gripping read, with complex characters, a plot that keeps you guessing and a great concept behind it all. One of the things I particularly enjoyed about this book was the exciting female protagonist, Elly, who leads the adventure very well and has real depth. However, this book deals with some dark ideas and may be disturbing for some readers, so I would be careful about recommending it to pupils without checking with parents first. If you are looking for a book with proper twists and danger at every bend, this is the book to read.