Parallel stories pit Malcolm against Kevin, a bullying, obnoxious new kid who goads Malcolm into beating him up; and Francis vies with his intimidating military-school commandant, who's presenting sex-education lectures. When Malcolm discovers that Kevin is only seven, he is guilt-stricken and tries to make amends by entering a charity marathon race. Meanwhile, Hal chops down the front-yard tree, alienating the neighbors (who can now see the house) but fascinating his sons with the wood-chipper.