A motorway service station on the M1: dimly lit, run down, poorly supervised, flickering lights, dark corners; a favourite stopover for long-distance lorry drivers on their way up north from London. Behind it, a body is found in a ditch, that of a girl barely out of her teens. She appears to have no family, no friends, no connections anywhere. Other girls have gone missing in the vicinity and no one has stepped forward to claim them. Anna Travis is assigned to the case. Her blood runs cold when she receives a letter from a lifer - someone she was responsible for arresting in the past - who writes to her from prison, asking her to visit him urgently. For he claims he knows who the killer is...