Overnight is the story of (Go figure!) an overnight birthday party. Within the first couple of chapters, one of the girls is kidnapped and the rest of the book chronicles the aftermath. It's written from different perspectives in alternating chapters.
It was okay. I guess. It just didn't do it for me. I've read plenty of books that deal with the intricate dynamics and bitchiness of middle school girls, and they're horrifying enough without throwing a kidnapping into the mix. That plot line just seemed unnecessary.