The book is about a bad king. He imprisons another king and makes the prince his jester's apprentice. The bad king treats them like animals and has them beaten.
Spoiler
Well, you just knew that the king and prince were going to be rescued eventually. So I was really hoping they would get the jester out too. But the jester decided to stay with the bad king... I didn't find that part of the ending very satisfying, and I also didn't really get it. Like, he didn't even really explain why. It was just kind of like, "Yeah, he starves me, and beats me, and it's cold, but meh, I'll just stay here." And the good guys were like, "Ok, we'll make him give you a blanket and some extra gruel though." The end. I really wanted a better ending than that for him.