In the Ardennes Forest on the Belgian border the French guns point north-east, awaiting the German onslaught. One reinforced-concrete blockhouse in the heart of the forest is manned, this winter of 1939/40, by Lieutenant Grange with three men, who live in a chalet built over it. Cut off from the rest of the world, their senses heightened to capture the sounds and smells of the forest, the men create their own security as autumn turns to winter. Later, though, when winter turns to spring, when the sap rises and the panzer divisions attack, Lieutenant Grange meets the fate he has never believed he would escape. But if this is a story of soldiers, it is not about fighting. It is about solitude, about watching and waiting - and about love, the young Lieutenant's devotion to Mona, the child-widow discovered like a sprite in the forest one rainy night, who, in this surreal period of suspense, becomes his lover.