I like Patricia McKillip because of her lovely writing style. She also writes really layered stories, and often just throws you into the action at the very beginning. That means that some of her books are down right confusing, and this one falls into that category.
Cyan Dag is a knight of the King of Yves, and on the eve of the King’s wedding, finds out that his perspective wife, the Lady of Skye, is actually a monster disguising herself as the Lady. So, he sets off for Skye to find the real lady, who is imprisoned in a tower. There’s a side story of a baker in a seaside town in Skye, and the Lord of Ysse, who is trying to wrest power back from the King of Yves. The stories are related, but it take a really long time to find out how.
This is still a lovely book, and I did ultimately enjoy it, but it would probably not be a great introduction to McKillip’s work – she can be much less convoluted, and those stories are better starters.