The Mysterious Benedict Society, by Trenton Lee Stewart, 2007

Reynie Muldoon's test-taking aptitude makes him a shoo-in for the opportunities and privileges offered by a mysterious, unnamed group. As an orphan, he has nothing to lose by accepting eccentric Mr. Benedict's offer to join his society along with three other unwanted children with curious talents. Their mission is dangerous, but it just might save the world. Sounds like a job for the Mysterious Benedict Society. Fun, nostalgic middle-grade adventure. Recommended.