Zelda is the alter- ego of Isobel Latimer, a quiet and self-effacing author whose life revolves around her husband's ill health and their financial problems. By becoming Zelda, and breaking into rauchy romantic thrillers, as opposed to her serious work, she and her agent, Troy, begin a clandestine series of rendezvous' around the country, promoting Zelda's books, and at the same time, start having an affair. So far, so good. But then it careers off out of control, with episodes of cross-dressing, gender transformation, and exactly who is role playing Zelda whilst dressed in the erotic underwear becomes less predictable. The ending, which I won't spoil, stretches belief a bit too far for me on many fronts, but like all Philippa Gregory's books, it's a very readable, if far fetched, novel.