1916, the eve of the battle of the Somme, and during a perilous night mission, Lieutenant Rafael Forrester witnesses a peculiar light followed by a vast explosion.   Wounded and delirious, Forrester finds himself shipped home to England, to the country house hospital of Sherston, where he learns he may face a court martial for the deaths of the men under his command.  Yet in the strange environs of Sherston, where any act of rebellion seems impossible, Forrester soon comes to fear for more than his freedom: haunted by hallucinatory dreams of his time at the front, he suspects he may be losing his mind.  Little does he realise that Sherston conceals its own incredible secrets, ones with the potential to change not only the course of the war but all of human history…