This third book in the series is a great combination of
The Adventures of Tom Sawyer
and The Terrible Two series, and is perfect for fans of Roald Dahl.
Tom a.k.a. the Great Brain, is off to boarding school.  Now his little brother, J.D., is free to follow in Tom's ingenious, conniving, and profitable footsteps.  All of J.D.'s attempts at turning a profit fail miserably, and he soon realizes that he just doesn't have that crafty Great Brain knack.  But when his younger brother is kidnapped, J.D. finds that his little brain may not be so ordinary after all . . .