During the wedding festivities of the king, Cyan Dag, a knight of Gloinmere, is sought out by a mysterious bard and told a terrifying tale: that the king has married a false queen--a lie cloaked in ancient and powerful sorcery. Spurred on by his steadfast honor and loyalty, Cyan departs on a dangerous quest to rescue the real queen from her tower prison, to prevent war, and to awaken magic in a land that has lost its way...
To be honest, when Cyan got his quest from the Bard of Skye, he was only asked to rescue the true queen. The false queen tried to warn him off by saying that if the true queen ever left her tower, she would die. That if she ever even looked at the world directly rather than through her enchanted mirror, she would die. So there was no way he could save her. But Cyan fought the false queen's sorcery to swear he'd find a way. Ill-prepared, he set out on his journey.
However, once he is on his way, we are promptly introduced to Melanthos, a baker's daughter in the land of Skye, and then Thayne Ysse, the oldest surviving son of the lord who had once ruled the North Islands.
Thayne's addition is more clear as to why he'd been added; he wants to find a way to take back the islands from the king of Yves, Cyan's king. A dragon and its hoard would be potent resources to that goal. His path crosses with Cyan's fairly early in the journey, so that the knight has more impetus to complete his quest quickly in order to return in time to save his king's life again. But Melanthos, in her tower with an ensorceled mirror of her own and the compulsion to embroider what she sees in it, is more passive, an observer. She is later joined by her mother who is stranger and becomes even more absorbed by the mirror than Melanthos. I often found myself questioning their importance to the story, especially since I couldn't remember how it ended. (I read it several years ago.)
Cyan tries hard to find the tower with the true lady of Skye. He faces setback after setback from being waylaid in the woods, to nearly being killed by Thayne, to finding a few wrong towers. But he persists in his quest even though his heart quails that he will ever succeed. Ultimately, the book is about his quest. It just turns out that there was more to his quest than he'd been told. Melanthos and her mother and Thayne were a part of that. Everything had a reason.
The Tower at Stony Wood is not an easy read. It's like one of those old fables rich in description and ancient magics. However, convoluted and meandering as the plot seemed, it was all carefully planned from the beginning. I thought it really paid off. I still don't want to read it all that often, but it is well worth reading every so often just to study the crafting. I recommend that you read it at least once to study the way she fit the story arcs together and builds her world. Just have patience. It's worth it.