Originally published as The Locked Room in Great Britain in 2022 by Quercus.

In London clearing out her mother's belongings, Ruth she discovers a photograph of her Norfolk cottage taken before Ruth lived there. The only clue is written on the back of the photo: Dawn, 1969. When COVID-19 rears its ugly head, Ruth has returned to the cottage. She and her daughter continue with work and lessons. The renter of the house next door, Sally, becomes a friend when they stand on their doorstep clapping for carers. Nelson, meanwhile, is investigating a series of suicides that could be the work of a serial killer. When he links them to an archaeological discovery, Nelson breaks curfew to visit the cottage to find Ruth chatting to her neighbour-- whom he remembers as Dawn Lancaster, a carer who was once tried for murdering her employer. When Ruth and Kate vanish, Nelson scrambles to find them before it's too late.