May 1915. While thousands of Britons fight in the trenches, a severely depleted polilce force remains behind to keep the home front safe.In London, the sinking of the Lusitania, sparks an unprecedented wave of anti-German riots and arson attacks across the city. Among the victims is the immigrant tailor Jacob Stein, found dead in his burnt-out shop.

Detective Inspector Harvey Marmion and Sergeant Joe Keedy must take on this case of cover-ups and contradictions and track down Jacob's killer - a hunt which carries them from the crime-ridden streets of wartime London to the chaos of the front line. But is the murder simply the result of a tragic excess of wartime hysteria, or perhaps a more premeditated crime?