I haven't read a book like this in a long, long time. It's got a Twilight Zone / X-Files feel, with weird crop circle / alien abduction scenes, but it's written in such a way that you never know whether you can trust the narrator, 12-year-old Simon.
He's obsessed with alien abductions, and his parents put him on medications to control what they've convinced themselves is obsessive behavior, but you never quite know with Simon what's real and what's imagined because he's also writing his own fantasy book and he gets so into his computer game he forgets the world even exists. He just somehow seems disconnected from reality, so when a plausible explanation for something he attributes to aliens comes along, the reader's not likely to trust him.
Then Simon goes camping and trips and falls and when he awakens, he's got a scar on his stomach. He's convinced it's proof he was experimented on while being abducted -- though his mom insists it's a tick bite. An older girl with a local MUFON chapter (I remember MUFON from my days as a newspaper reporter!) believes his story and they're off and investigating, running for their lives.
I won't ruin it with the awesome twist at the end. You'll have to read it yourself to find out what happens. Even at the very, very end...I was still left wondering...was it real? Or was it all in Simon's mind?