Parents, caveat emptor! The storyline is brutal. Even though the writing is geared for young adults, the main characters are teenagers, there's very little physical romance, and the actual violence would probably count as PG-13 nowadays... it's probably one of the most terrifying books I've read in a very long time! Right up there with George R.R. Martin, if not more so. Remember what we learned from Jaws: you don't actually need to SEE the shark in order for it to be terrifying. Sometimes not seeing the shark is even worse.
The story is basically about a teenager who is forced to compete in a 24-man-enter-1-man-leaves event. I don't want to spoil it by saying any more, but if you liked The Running Man, you'll definitely like this. And if you're young enough that you don't remember The Running Man, nor did you get the Thunderdome reference, then I'm just way too old. But take an old fogey's advice and read this book.