It is December 1913 and Detective Constable Frank Bolam has a murder to solve. The victim is found drowned in the River Wear with a vicious knife wound to his lower back. There are no witnesses and no clues. A few months later another body is found with the same vicious knife wound, followed closely by a further two murders with the victims stabbed in a similar manner. This is a clever killer. No clues are found and Bolam cannot find a way to break the deadlock in his most perplexing case. Having risen from a lowly mining family, Bolam has strong moral values and becomes totally obsessed with the killer and the devastating sadness brought to the victims' relatives. He vows to bring the murderer to justice, whatever the cost. These are turbulent times, with the country in the middle of an attritional war. In his quest to find the murderer, Bolam follows his hunch and enlists in the army, heading for the trenches to track down a cold-blooded killer in the middle of the most mechanised slaughter the world has known.