Ruth is in London clearing out her mother's belongings when she makes a surprising discovery: a photograph of her Norfolk cottage taken before Ruth lived there. Her mother always hated the cottage, so why does she have a picture of it? As she died three years ago, Ruth can't exactly ask her, and her father denies all knowledge of the picture. The only clue is written on the back of the photo: Dawn, 1969. Ruth returns to Norfolk determined to solve the mystery, but then Covid-19 rears its ugly head. Ruth and her daughter are locked down in their cottage. Happily the house next door is rented by a nice woman called Zoe, who they become friendly with while standing on their doorstep clapping for carers. Nelson, meanwhile, has no time to be bored. He's investigating a series of suicides that could be the work of a serial killer. It's only when he links them to an archaeological discovery that he thinks of Ruth.