March 1946. The railways are falling apart, rationing is getting worse and black-marketeers are at work. For Violet McIntyre, a dressmaker living in Woodford Halse, it is a struggle to make ends meet. Her life becomes inextricably linked to an investigation that Detective Inspector Charles Vignoles of the Railway Detective Department is pursuing. Vignoles believes he's making good progress tracking a gang of money counterfeiters, but when two young cleaners from Woodford engine shed make a startling discovery, everything spirals out of control. The Inspector struggles to understand the worsening situation, and like the smoke from the grimy engines that gets in his eyes, his judgement becomes clouded. But he cannot afford to make a mistake - a woman's life may depend upon it!