A review by readoodles
The Mysterious Benedict Society by Trenton Lee Stewart

4.0

The world labors under gloom. Mr. Curtain oozes mind control and some people have lost their memories while others are crabby and angry. Mr. Benedict fears it may be too late to halt the world emergency, but he places an ad to attract the brightest children. Reynie, Stickie, Kate and Constance pass the test. Mr. Benedict sends them off to save the world... if they can.

http://www.mysteriousbenedictsociety.com