This book takes place in an alternate history, set in the UK. There are three identical boys in what appears to be some kind of orphanage. They are being cared for by three women that are taking shifts and are called Mother. For instance the woman that wakes them at the start of the day is Mother Morning. She notes each of their dreams down in a large book.
The children are given medication every day, and are told that it is to help with a bug that they have contracted. It turns out though that they are clones of a serial killer, and the drugs in fact are going through medical trials with the notes taken on their effects on the children being used for the research. One particular detail I liked was that the children are told that Margate is a wonderful and dream-like holiday destination with a wide variety of rides and games. This is where all of the other children that are no longer around are living. The remaining few are desperate for their chance to head to Margate.
I thought it was very well written, and the drip feed of new information throughout the book was paced just right.