I wish I remembered more about King Lear, but it's been nearly 30 years since I read it in high school. Then again, I'm not sure it would have made much difference; in the Author's Note at the end of Christopher Moore's Fool, he acknowledges being pretty free in adapting the source material. To the best of my recollection, the basic plotline is followed: the aging king is duped by two of his ambitious daughters into disinheriting the third one, and quickly comes to regret it. Much intrigue, duplicity, and death follow. It is a Shakespearean tragedy, after all.
However, in Moore's hands, it becomes a tragicomedy, at times bordering on farce, with much bawdiness. If you've read anything else he's written, you'll expect nothing less.
I actually don't remember much about the king's Fool from the play at all, but here, his perspective takes the primary role. Pocket - so named because he was a particularly tiny baby when he was found abandoned on the steps of a convent - was raised by nuns, became part of performing troupe, and found a home in King Lear's court when he was able to coax laughter out of the king's youngest daughter, who had been mute since losing her mother. Although Pocket was officially Cordelia's Fool, her older sisters Goneril and Regan found their own uses for him as well. And from the Fool's unique position within the court, Pocket plays the pivotal behind-the-scenes role in orchestrating both the fallout and the resolution of Lear's choice.
While following the events of the play, including fragments from some of its best-known speeches, Moore has also worked in elements from other Shakespearean plays, most notably Macbeth's witches. I had some trouble keeping characters straight, but I think that goes back to the source material more than to what Moore has done with it. What he's created is by no means a primer on Shakespeare, British royalty, or the Middle Ages, but it is a fun read. If you haven't been exposed to Moore's brand of creative absurdity before, I'm not sure I'd suggest starting here, and even fans have had mixed reviews of Fool. Having said all that, though, there were plenty of places in the book where I laughed out loud, and I found it enjoyable and clever. And while bawdiness isn't generally my thing, Moore writes an element of something resembling affection into it that makes it more appealing to me than it might be otherwise.
It wouldn't be the first time Christopher Moore has made something - zombies, humpback whales and aliens, death - more appealing to me than it might be otherwise, though. Although Fool may not end up being my favorite novel of his, it doesn't change his place among my favorite writers.