Stella Darnell cannot shake her father's legacy. A year after his death, she still visits his house every day. Now she has discovered what looks like an unsolved case in his darkroom: a folder of unlabelled photographs of deserted streets. But why did her father - a Detective Chief Superintendent and a stickler for order - never file them at the station? The oldest photo dates back to 1966. To a day when a young girl, just ten years old, is taking her little brother home from school in time for tea. That afternoon, as the Moors Murderers are sent to prison for life, Mary witnesses something horrible that will haunt her forever.