The reigning queen of historical fiction" Fiona Davis, New York Times bestselling author of The Lions of Fifth Avenue The New York Times and Usa Today bestselling author of The Huntress and The Alice Network returns with another heart-stopping World War Ii story of three female code breakers at Bletchley Park and the spy they must root out after the war is over. 1940. As England prepares to fight the Nazis, three very different women answer the call to mysterious country estate Bletchley Park, where the best minds in Britain train to break German military codes. Vivacious debutante Osla is the girl who has everything beauty, wealth, and the dashing Prince Philip of Greece sending her roses but she burns to prove herself as more than a society girl, and puts her fluent German to use as a translator of decoded enemy secrets. Imperious self-made Mab, product of east-end London poverty, works the legendary codebreaking machines as she conceals old wounds and looks for a socially advantageous husband. Both Osla and Mab are quick to see the potential in local village spinster Beth, whose shyness conceals a brilliant facility with puzzles, and soon Beth spreads her wings as one of the Park's few female cryptanalysts. But war, loss, and the impossible pressure of secrecy will tear the three apart. 1947.