Lois's nightmare parents, Victor and Ida, come for a surprise visit and throw the family into turmoil not only with their mere presence, but by promising to pay for a much-needed refrigerator and then reneging after Lois and Hal spend money they don't have. Lois and Hal are forced to ask Ida and Victor to stay longer to help take care of the kids while they work some crazy overtime. Victor treats Reese like a king while Ida tortures Malcolm for being a smart wimp. Victor gives Reese a live grenade, and when Reese inevitably arms it, Malcolm's quick thinking blows up the new refrigerator instead of the whole house. Hal extorts money out of Lois's parents to pay for the damage. Francis motivates his fellow cadets to break out for a weekend and go to New Orleans for Mardi Gras, but then spend the entire time there suffering from eating bad sushi.
Malcolm is a regular high school kid trying to navigate his way through life despite the various obstacles thrown in his way a complete misunderstanding of girls, the constant burden of masterminding plans to get himself and his brothers into or out of trouble, and a miserable job at the Lucky Aide not to mention a severe case of teen angst.
Although Malcolm has a genius IQ, he can't seem to make sense of the opposite sex, much less his embarrassing family. Lois is the outspoken, opinionated mom, who still manages to rule the roost even though her boys are growing wise to her crafty ways. Hal, a dad who is just a bumbling, big kid at heart, often finds himself creating more chaos than his five boys combined.