Rooney has cleverly used fact, weaving it seamlessly into fiction. The shades of Burgess and Maclean waft through the novel under other names, while Melita Norwood, Rooney's original inspiration for the story, is a vital presence, although Rooney's heroine, Joan, is not intended to be a reflection, and is markedly different, not least in her political beliefs, and motivation for spying.
A brief synopsis - Nick Stanley, a QC, and pillar of the establishment, is astonished to discover that his elderly mother is being questioned by the Security Services, who believe she was part of an atomic spy ring. He is even more astonished to discover that the accusation happens to be true.
Moving between now and the Cambridge of the 1930s-50s, this is a wonderfully well written tale. As a straight spy thriller it works brilliantly. Rooney is excellent at building up the tension. But where she really excels is in portraying the complications of that most complex of eras.
Joan is a most unlikely spy, and not just because she's a woman from an impeccable middle-class background. She has a vague allegiance to Communism, she has some nebulous socialist beliefs, and her boyfriend, who will become her Russian controller, is an ardent fellow-traveller. But politics doesn't really mean that much to her; and she quickly becomes disenchanted with the Soviet model, realising that in Stalin's Russia everything is not quite what it seems. Some of her friends are drawn to spying by political or social beliefs, some are in a prime position to be exploited because of their sexuality, others - like Joan - will be horrified by the part they played in the project to build the atom bomb, and use passing secrets from the project as a form of absolution for Hiroshima and Nagasaki.
It's a complex portrait of the anatomy of spying and the early days of the Cold War; and the complexities of human relationships. Rooney's characters are engaging, and the historical background is excellent. For a blast of the Cold War, you can't do much better than Red Joan.