On a sunny afternoon in late June, 1914, Cambridge don, Joseph Reavley is summoned from a student cricket match to learn that his parents have died in a road accident.  Joseph’s brother, Matthew, as an officer in the Intelligence Service, reveals that their father had been en route to London to turn over to him a secret document – allegedly with the power to England and damage the British Empire.  At the same time, events in Sarajevo will propel Europe, and the whole world, into war.  But there are some tragic deaths on the home front and where is this mysterious document...if it exists at all?

By April 1915, Captain Joseph Reavley, now a chaplain in the army, attends to his soldiers in the trenches.  An arrogant young war correspondent, Eldon Prentice, nephew of the respected General Cullingford, is found dead in ‘no man’s land’.  But he has not been killed by enemy fire.  Joseph has his suspicions as does his sister Judith, who is driver to General Cullingford.  Behind the scenes, the man the Reavley’s have nicknamed ‘The Peacemaker’ is sabotaging Britain’s war effort.

In March 1916, Joseph Reavley is still at the front, at Ypres, as is Judith, now an ambulance driver.  By the time Joseph returns to the family home in tranquil Cambridgeshire, rumours of spies and traitors are rampant.  And when the savagely brutalised body of a brilliant weapons scientist is found, it must be suspected that the Peacemaker has been at work...again.

July 1917 finds Joseph and Judith at Passchendaele, and among the fatalities is the trusted commanding officer of Joseph’s regiment.  Into his place steps the pompous and incompetent son of a general, but soon he, too, is dead, killed by his own men.  Twelve men are arrested, including a courageous doctor who has been put forward for the Victoria Cross.  And behind the scenes the Peacemaker continues his sabotage...

In late 1918 and end to the conflict seems in sight.  Behind the lines, violence is increasing and there is abuse of German prisoners.  When a nurse is raped and killed, the prisoners are suspected.  The Peacemaker’s German counterpart has crossed the lines and is about to reveal the identity of the Peacemaker, but can Matthew rescue him in time...