Occupied Paris, 1940. A woman in a red hat and a black fur coat hurries down a side-street. She is Mathilde Carre, codenamed 'the Cat', later known as Agent Victoire. She is charismatic, daring, and a spy; her story is one of heroism and survival against the odds.

These are the darkest days for France, half-occupied by Nazi Germany, half-governed by the collaborationist Vichy regime; and dark days for Britain, isolated and under threat of invasion. Yet Mathilde is driven by a sense of destiny that she will be her nation's saviour.

With little training or support, Mathilde and her Polish collaborator, Roman Czerniawski, create a huge web of agents in a matter of weeks to form the first great Allied intelligence network of the Second World War. They risk torture and execution to deliver their coded reports, London's sole source of reliable information about the Occupation.

But the 'Big Network' is threatened at every turn and when the Germans inevitably close in Mathilde makes a desperate compromise. She enters a hall of mirrors in which any bond is doubtful and every action could be fatal. Nobody is certain where her allegiances lie - her German handler, the founder of the Resistance she ensnares and the British who eventually succeed in extracting her on a fast boat all have to make their own calculations. Is she a double, possibly even a triple agent, and, if so, can she be trusted to turn yet again?

Victoire is the story of a passionate, courageous spy but also of a fragile hero, desperate to belong - a portrait of patriotism and survival in momentous times. Drawing on a wide range of new and first-hand material, Roland Philipps has written a dazzling tale of audacity, complicity and the choices made in wartime.