It's 1941. Imagine you're Winston Churchill.

The Battle of the Atlantic is a disaster. Supply ships ferrying vital weapons, food and fuel from North America are being torpedoed by the German U-boats.

You are concealing from the country the number of ships sunk. You are concealing the number of men killed. Without the supply ships Britain will starve. The tide of the war is turning in Germany's favour.

This is the story of the game of battleships that won the Second World War. In 1941 Prime Minster Winston Churchill gathered a group of unlikely heroes - a retired naval captain and eight brilliant young women, the youngest only seventeen years-old - to form a secret strategy unit. On the top floor of a ramshackle HQ in Liverpool, the Western Approaches Tactical Unit spent day and night playing war games to crack the U-boat tactics.

A GAME OF BIRDS AND WOLVES takes us from the steamy fug of a U-boat as the German aces coordinate their wolfpack, to the tense atmosphere of operation room as the British team plot battles at sea on the map. The story of Operation Raspberry and its unsung heroines has never been told before. Investigative journalist Simon Parkin brings these hidden figures into the light in this gripping tale of war at sea.