The Squire's Quest by Gerald Morris

In this book our attention returns to Gawain's squire, Terence, who has aged, but is still pretty sharp. He's worried because he hasn't heard from his family at Avalon for quite some time. Furthermore, a young man called Mordred has turned up at court, and while he impresses almost everyone, a few (including Terence and Kai) remain skeptical. There's a long bit with the Emperor of the Roman Empire (in Constantinople) and a Romeo and Juliet type plot, too. Overall, I liked this book; it seems to be shoring things up as they draw toward a conclusion.