When the body of Holly Campbell is found on the train tracks to Glasgow Central, the police decide it’s a clear suicide. She was a troubled young woman. She’d tried before.But Sergeant May Mackay can’t let one detail go. The ticket found in Holly’s pocket.If Holly never wanted to come home, why did she buy a return ticket?As Sergeant Mackay looks into this question, she realises that one ticket can lead to dangerous alleyways, forgotten paths and a terrifying network of secrets.