1865. A passenger train stands ready to depart amid the bustle at York station. The flurry of passengers and porters, the swooping pigeons and barking dogs are thrown into a state of turmoil when an explosion rips through the brake van of the train killing guard Jack Follis.

In response to a summons from the North Eastern Railway, Inspector Robert Colbeck and Sergeant Leeming are sent to investigate. Was it an accident, deliberate vandalism or targeted murder? The longer the investigation goes on, the more complex it becomes. With a dizzying array of suspects and motives, will the combined skills of the detectives be enough to identify and catch the culprit?