The story begins with Will getting over mono, which I can attest leaves you feeling like utter crud for a long time. In going to his Uncle's house in Wales, he stumbles into the next big event of magic, facing a power unlike he's ever faced before: the Grey King. New to the book is Bran, an albino boy that makes quick friends with Will, and has secrets of his own, ones that even he doesn't know exist.
And Will does stuff, and it all turns out, without really mattering, because this is a Susan Cooper book. Am I being too hard on her? No. In her first book, she created a work entirely powered by the characters actions and interactions. I know that she can write that way. I understand that some books are about the journey, but holy guacamole, when the journey is wandering about with fate blowing like a hurricane force wind, the journey feels pointless. And then you get to the end and blam, it's the end, and what the hell was all that about?
To complement Susan, she hamstrings Will's powerful magic enough to make him interesting. To do great magic is to get attention, and to get attention means trouble.
Even if I had been the right age for this book, I would never have gotten through it. I would have stopped halfway through, bored.
So there you have it. Beautifully written and dreadfully dull, the Grey King resembles its own name. That's a sad literary trick that nobody else should emulate.