The Mysterious Benedict Society by Trenton Lee Stewart

My name is Constance, and I'll call you whatever I want to. I don't know why Benedict allowed me to pass all of his tests, but he's put me on a "team" with three other weird kids. Stinky memorizes everything he sees, but the kid is ridiculously nervous. Kate carries a stupid bucket around where she holds "useful" things like a kaleidoscope. Reynie seems kind of normal, and he's the only one willing to give me a chance. I know I'm a pain and mouthy, but I'm going to give him a chance too. Benedict thinks our team (I came up with the name Mysterious Benedict Society) is the only hope for stopping the Emergency. Someone is sending hidden messages through televisions and radios, but we don't know why. Benedict thinks they're coming from a private school on an island, so he's going to send us there as students. I don't know why he'd send kids into a dangerous situation, but I'm going to go anyhow. It's my choice, not his. 

The plot contains a lot of thinking, as the kids try to figure out what's going on with the Emergency. Most of the book takes place at the private school where the kids try to excel in the strange classes. They try to advance to a higher level where they'll gain access to more secrets. The director is clearly manipulating the minds of the students and public, but he has an unexpected connection to Mr. Benedict. This becomes important to resolving the conflict, although the problem will continue in the book's sequel. As mentioned above, the main characters are a strange blend of personalities. The most entertaining part of the book is how they work together in unconventional ways. Reynie becomes the leader and is able to think through and solve perplexing problems. Kate is impulsive but athletic, Sticky is very book smart but anxious, and Constance is just plain difficult. The others don't understand why Constance is part of the team, but her personality is important during the climax. All of the kids have issues with their family situations, but the plot's resolution brings everything to a happy conclusion. Overall, the book was very entertaining, and I recommend you give it a shot. The movie follows the gist of the book, but the book is almost always better.