The Mysterious Case of the Alperton Angels by Janice Hallett

Open the safe deposit box. Inside you will find research material for a true crime book. You must read the documents, then make a decision. Will you destroy them? Or will you take them to the police?
Everyone knows the story of the Alperton Angels: the cult-like group who were convinced one of their member’s babies was the anti-Christ, and they had a divine mission to kill it – until the baby’s mother, Holly, came to her senses and called the police. The Angels committed suicide rather than go to prison, and Holly – and the baby – disappeared into the care system.
Nearly two decades later, true-crime author Amanda Bailey is writing a book on the Angels. The Alperton baby has turned eighteen and can finally be interviewed – if Amanda can find them, it will be the true-crime scoop of the year, and will save her flagging career. But rival author Oliver Menzies is just as smart, better connected, and is also on the baby’s trail.
As Amanda and Oliver are forced to collaborate, they realise that what everyone thinks they know about the Angels is wrong, and the truth is something much darker and stranger than they’d ever imagined.

This story is far from over – and it won’t have a happy ending.