December 1860. Headed for the morning shift at the Swindon Locomotive works is an army of men pouring out of terraced houses built by the GWR, a miniature town and planned community that aims to provide for its employees from cradle to grave. Unfortunately, boiler smith Frank Rodman is headed for the grave sooner than he'd expected, or he will be once his missing head is found.

Colbeck, the Railway Detective, finds his investigation into Rodman's murder mired in contradictions. Was the victim a short-tempered brawler, or a committed Christian and chorister who aimed to better himself? On the trail of Rodman's enemy as the season starts to bite, Colbeck finds little festive cheer in the twists and turns of this peculiar case.