En octubre de 1918 parece que se vislumbra el final de la guerra. Los hermanos Reavley -Matthew, agente de los servicios de inteligencia británicos, Joseph y Judith- se encuentran en las terribles trincheras de Flandes. A lo largo de la serie, no han cejado en su afán de dar con quien mató a sus padres: el Pacificador, un ser empeñado en evitar la victoria británica. Cuando están a punto de localizarlo, Matthew es acusado de asesinato.

After four long years, peace is finally in sight, but Chaplain Joseph Reavley and his sister Judith, an ambulance driver on the Western Front, are more pressed than ever as they deal with increasing violence behind the lines. Their brother Matthew, an intelligence expert, continues his pursuit of the Peacemaker, who has been trying to undermine the public's support of the war effort. A German counterpart has offered to expose his co-conspirator as a traitor, but with secret informers everywhere, the mission would be fraught with hazards.