Who was Kitty Harris? Born in London to an emigre Jewish family she was a key figure in Soviet espionage networks across the globe, running agents in London, Berlin, Shanghai, Mexico and Los Alamos. She was Donald Maclean's controller and lover in London and Paris; and was the bigamous wife of Earl Browder, General-Secretary to the American Communist Party. She also played a role in the penetration of the Manhattan Project, which developed the atomic bomb, and helped organize an illegal spy-ring in Mexico City. A master of disguise and different identities, Kitty Harris was thought to have disappeared in the Soviet Union, but her extraordinary story can now be told by a senior Russian intelligence officer who has had access to her astonishing archive.