After joining the basketball team at school, Malcolm soon finds himself under the coach's skin due to his constant complaining, which eventually gets him kicked off the team. Determined to put an end to his horrible habit of talking before he thinks, Malcolm starts "holding his tongue" which solves all the problems with his coach, girlfriend, and parents, but it ends up causing more stress than before. Meanwhile, Hal takes up speed walking and is desperate to be the best while Reese gets Craig to take him and Allison to a concert and almost ruins his date.
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.