February, 1944. A bitter winter grips occupied France, where Marc Reece leads a circuit of British agents risking their lives in order to sabotage the German war effort from within. But Reece has a second mission, secret even from his fellow agents - including Charlotte, the woman with whom he has ill-advisedly fallen in love. He must secure a document identifying a German spy at the heart of British intelligence. The fate of the Allied forces on D-Day is in his hands.

But when his circuit is ambushed - with fatal consequences - Reece realises there may be a traitor in its ranks, putting everything they've been fighting for at risk. Then Charlotte goes missing. Is she in danger, or has Reece been betrayed by the only person he thought he could trust? And with the clock ticking towards D-Day, can he find the truth before it's too late?

A gripping and atmospheric thriller inspired by true events, this is the story of a deadly game of espionage, destined to change the course of the most crucial battle in the Second World War.