This was the best book of them all, and should always be included in the "Trilogy"as it has as much to do with the story as the rest. Though Mary Stewart wrote 3 great books, (read them all several times) the last book did not feel as an add on, but as the obvious conclusion. Much of the story hinges on Morgan becoming pregnant with her half brother, Arthur's son. Most authors about the Arthurian Legends made the son evil. But in Stewart's book, he is not evil. One should not read the Trilogy without reading the 4th book. It is, the most interesting and believable conclusion to the rest of the stories about the legend of King Arthur. Most of the ones I've read are terrible. But this series is great.