When Lois buys a brand-new king-sized bed, Hal thinks that her motive is to put more distance between them and refuses to sleep in it. Moved to tears by an opera he sees on television, Dewey is inspired to write his own operatic masterpiece, "The Marriage Bed," which is based on his parents' fight and turned into a school production. Meanwhile, Malcolm and Reese build their own street luge board; and Jamie falls head over heels for the baby girl across the street.

After Lois and Hal are reminded of the tight budget they must uphold, Hal discovers one of his boys has been dialing a 900 number. His attempt to explain the error to the hotline's billing department turns awry when he forgets to hang up the phone, incurring a whopping $800 charge. Meanwhile, Reese takes a job at a research clinic that pays him to pop experimental pills, and a reluctant Malcolm takes on a mortifying job at the Lucky Aide as a costumed Uncle Sam on stilts.

When Hal catches Dewey smoking, he makes a deal with him that he will stop drinking coffee if Dewey quits smoking.

Lois, Hal, and Dewey go out of town for a piano competition, so they get Ida to watch over Malcolm and Reese while they're gone. Since Ida thinks Reese needs to become a man, she comes up with a competition for Malcolm and Reese, and if Reese wins, he can take Raduca as his bride. Now, when Lois and Hal return, they're surprised to find out that Reese has run away to Las Vegas to get married.

Malcolm struggles with his speech when he's elected valedictorian of his graduating class at school. However, Lois refuses to listen to any of his complaints and reveals that she wants him to become President of the United States. Meanwhile, Reese does everything he can to get a permanent job as a high school janitor, which includes creating the most disgusting mess ever. In the meantime, Hal has problems with Malcolm's Harvard tuition, while Francis finally gets a real 9-5 job that he actually enjoys. Also returning for the family celebrations is Grandma Ida, as they all say goodbye to Malcolm when he leaves for college.