Between 1941 and 1944, 16,000 plucky homing pigeons were dropped in an arc from Bordeaux to Copenhagen as part of ‘Columba’ – a secret British operation to bring back intelligence from those living under Nazi occupation. The messages flooded back written on tiny pieces of rice paper tucked into canisters and tied to the legs of the birds. Authentic voices from rural France, the Netherlands and Belgium, they were sometimes comic, often tragic and occasionally invaluable with details of German troop movements and fortifications, new Nazi weapons, radar system or the deployment of the feared V-1 and V-2 rockets that terrorised London. At the centre of the story is the ‘Leopold Vindictive’ network – a small group of Belgian villagers prepared to take huge risks. They were led by an extraordinary priest, Joseph Raskin, a man whose intelligence was so valuable it was shown to Churchill, leading MI6 to parachute agents in to assist him.