It is the time of The Great Configuration, a once in a hundred years event. Family and monsters descend on Rookhaven from all over the country to take part. But amid the guests there is an interloper. One who is disguised and has an eye on their destruction.
Meanwhile Mirabelle – part human, part monster – discovers that to those from outside Rookhaven she is not considered family at all… and, forced to search further afield for knowledge of her true history, she risks everything – and everyone.