1865. A passenger train stands in York station. Jack Follis, the guard, patrols the platform to make sure that everyone is safely aboard. Returning to the brake van to load a box into it, he is alarmed by a smell of burning. Before he can find the cause, there is an explosion and the van is engulfed in flames. Responding to summons from the North-Eastern Railway, Robert Colbeck and Victor Leeming are sent to investigate. The two are split on whether a murder has taken place. Although the information they received was scant, Colbeck is convinced this is a murder case. The longer the investigation goes on, the more complex it becomes. Guilt shifts at a bewildering speed. It will take the combined skills of the detectives to identify and catch the person responsible for causing Jack Follis' death.