On the eve of the Battle of the Somme, a group of officers make a reckless promise that any survivors will meet after the war and race from Paris to the Mediterranean. Years later, a motorcar crash in England and a sequence of suspicious deaths suggest that the pact has become a method of revenge. Rutledge retraces journeys through France and southern England to discover which survivor is killing the others and what happened before the offensive began.
The novel connects the exhilaration of early motoring with the fatalism of men expecting to die. A private ritual created under battle pressure survives into peace, where guilt and rivalry have had time to deepen. For Rutledge, the Somme is both evidence and personal catastrophe, making the case one of his most direct confrontations with the war.