"The New York Times bestselling author of The Spy and the Traitor tells the thrilling true story of the most important female spy in history: an agent code-named "Sonya," who set the stage for the Cold War. In 1942, in a quiet village in the leafy English Cotswolds, a thin, elegant woman lived in a small cottage with her three children and her husband, who worked as a machinist nearby. Ursula Burton was friendly but reserved, and spoke English with...