I've just finished reading Scary Mary, and I've got to say I wasn't impressed. That isn't to say that it isn't a decent book, because it is. In fact, if it had just a bit more editing, it would be quite good. But it has quite a few instances of Classic Hockings (that is, when there is very noticeably a random word missing in a sentence, and it's a word that really should be there) and many sentences that are a comma away from being grammatically perfect.
The basic plot: Mary lives with her Gran, who tells fortunes and communicates with the dead for profit. Mary isn't really well liked at school because of this (and other reasons) and is called a freak. She starts to become friends with Cy, a new kid in school. Her rival, Vicky, a cheerleader, immediately starts plotting a way to separate the two, and eventually succeeds when Cy invites Mary over during a school dance.
She decides to show Cy what a freak Mary is by coercing her into trying to channel River Phoenix on a Ouija board. They succeed in channeling a spirit, but it's definitely not River Phoenix. When the spirit turns out to be homicidal and Mary tries to warn Cy about this, he shuts her out.
I won't give away anything further than that in case you want to read this book, but past that it gets extremely predictable and some of the references made are a bit dated. The teenagers don't really talk like teens (outside of some of the wild things that Mary tells her guidance counselor, who reads as more of a stalker than a guidance counselor) and the pacing is a bit wonky.
Honestly, I probably will read the sequel at a later date, but overall this book was pretty forgettable. It was a nice little diversion, and definitely a good way to ease my way back into reading and reviewing for the general public, but it will not be making any top 10 lists of mine anytime soon, unless it's the top 10 meh books list.