This book actually contains books which are available separately: "The Green Knight", "The King's Damosel", and "The King's Daughter". These are all great stories, bringing the stories of three women from Arthurian times to the reader. The three stories are united by the character of Morgan le Fay, whose malice against her half-brother and desire for power bring her to various acts of magic and cruelty. The heroines of the stories are Vivian, the granddaughter of Merlin and Nimue, Lynett, married to Gaheris but in love with Gareth and wanting more than her prospects seem to allow, and Ursulet, daughter of Arthur and Guinevere. Each character meets a studly hero whom she ends up in love with, although not every story ends happily-ever-after. Morgan frequently uses human frailties and desires against the heroes, and the characters struggle to achieve some kind of peace and happiness.
One more thing you should know--the story of "The King's Damosel" was very loosely the basis for a film "Quest for Camelot", although Chapman's story is much more realistic and touching than the film managed to be.
If you want three books for the price of one, and all good stories of King Arthur's time (more or less), this is the one to buy.