"When her professor told Sommer Kappel that her life would never be the same, she had no idea that she would become a single mother, a British agent, or work with Germany's mathematics genius to create a secret weapon that turned out to be an atomic bomb, or be hounded constantly by a rogue Gestapo agent. When things were the blackest, she discovered she was pregnant and met a handsome British army officer, who quietly fell in love with her and risked...