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 hard pressed than ever. Behind the lines, violence is increasing: soldiers are abusing German prisoners, a nurse has been raped and murdered, and the sinister ideologue called the Peacemaker now threatens to undermine the peace just as he did the war. Then Matthew, the third Reavley sibling and an intelligence expert, suddenly arrives at the front with startling news. The Peacemaker's German counterpart has offered to go to England and expose his co-conspirator as a traitor. But with war still raging and prejudices inflamed, such a journey would be fraught with hazards, especially since the Peacemaker has secret informers everywhere, even on the battlefield.