Malcolm finds his life as the middle brother in an eccentric family made even more difficult by his being placed in a class for gifted students at school where he reluctantly befriends another boy with a high IQ and stands up to a bully.

Lois and Hal leave the boys alone for the weekend with Francis. the boys assume that if all goes well, Francis may not have to go back to military school.

Francis goes AWOL from military school to link up with his girlfriend, a ditsy doozy who's made him gaga.

The whole family attends a Krelboyne family picnic, and Malcolm dreads his performance in the event's Academic Circus will make him look like a freak. Disasters abound as stage acts bomb, families feud, and Malcolm's dad serves meat to vegetarians.

Lois's firing prompts household economizing. Meanwhile, Francis delights in his honor-guard duty—at a teenage beauty pageant.

While Hal secretly takes the boys to the stock car races, Lois desperately searches for her missing paycheck. Francis at military school is keeping a boa constrictor as a pet.

A spiffy cheerleader attracts slovenly Reese, who cleans up his act—best as he can—to woo her. He even joins her rah-rah squad. Dewey tries to convince Lois and Hal to buy him a new toy. Francis has a heart-to-heart conversation with headmaster Spangler.

Hal, Loi, Malcolm and Reese are trapped in a horrendous traffic jam. Francis enters himself in a bet that recalls the egg-eating wager in "Cool Hand Luke." Malcolm becomes smitten over a girl he meets. Dewey has his own little adventure--all over the world--before his family returns home.

Francis visits the week after Halloween and helps his brothers in a trick that involves a giant slingshot with icky ammo. Hal tries to catch a mysterious hot-rodder.

A family weekend vacation to a casino turns into an ordeal in the desert for Hal, Reese and Malcolm, who wander onto an artillery range. Francis sneaks home, but has no one to play with.

The night shift at Lucky Aide is held hostage by two robbers, since Craig does not want to give up the combination for the store's safe. Francis tries to help a heartbroken friend at the academy, while Hal and the boys fight nature at home.

Dewey starts carrying a purse to school. Francis's friend Richie joins him at military school. Malcolm becomes a slave to an old woman in the neighborhood.

Lois' estranged parents, Ida and Victor, pay the family a visit. Right away, trouble starts brewing. Victor bonds with Reese, Ida gets Malcolm into a fight, and Dewey is haunted by childhood memories of his inattentive grandparents.

Malcolm and Reese go to a bowling party where they vie for the attention of a cute girl.

Francis has an extra ticket for a wrestling event and it is the prize pitting Malcolm vs. Reese in a one-upmanship war; caring for Craig's cat is troublesome for Dewey.

Hal is inadvertently responsible for a toxic chemical spill that forces a neighborhood evacuation; Malcolm deals with being grounded even in the emergency shelter; Francis suffers through a date with a geeky 12-year-old.

The family takes a vacation with the Kenarbans, sharing a houseboat. And while Steve's parents are caught in a fight, Reese and Steve socialize with some cheerleader from a nearby spirit camp, Malcolm is stuck with Hal fishing. At the military academy, Eric turns eighteen and leaves for Alaska, inspiring Francis to do something about his situation too.

Lois, in an attempt to get a break from the family, joins a book club that turns out to be a night off for frustrated housewives, but it all goes a little bit haywire. Meanwhile Francis tries to get to Alaska, learning something important about himself and about truck drivers. Hal, who tries to keep the boys out of troubles for the evening, is caught in an inner conflict about how to treat them.

When Hal's doctor discovers something suspicious during his routine check-up, Lois and Hal become frantic, nervous wrecks as they wait for the test results. As a result of her anticipation, Lois becomes even stricter with the boys, leaving them to misinterpret the new house rules. Meanwhile, in Alaska, Francis comes to blows with his boss.

Trouble finds Reese at his new fast-food job; a new Krelboyne tutors Malcolm; Hal and Lois sabotage Dewey's plan to get a dog.

Juicy guest casting and ingenious plotting enliven an hourlong episode that airs in the plum post-Super Bowl slot. One storyline unfolds at Hal's company picnic, where Lois clashes with a blabby wife and her beleaguered spouse; and Hal runs afoul of his new boss and the big cheese. In Alaska, Francis's scheme to win a bet involves rigging a hockey game that pits loggers vs. a fearsome women's squad led by a blowhard coach.

After Hal is mistaken by his new boss, as that guy's boss, Hal plays along. Malcolm is in a three-legged scavenger hunt with the girl he likes, but becomes upset after he confesses he likes her, and she says she likes another boy. Reese is also the the scavenger hunt, and at first doesn't like the big dumb bully he is with, but they grow to like each other when they bond over beating up the other contestants and stealing their items. Lois continues to balance keeping Dewey intact and dealing with the crazy woman, but now must talk to the husband as well. Francis continues to sabotage his own team, this time on the ice.

Malcolm, whose frenetic home life is a kind of zoo, begins the fourth season by accompanying his family to the real thing. A visit to the zoo offers close encounters with creatures great and small. But Hal wishes he could have passed on an encounter with Lois's former beau, who lectures on rain-forest animals. Elsewhere, Reese butts heads with a goat; and Malcolm and Dewey take a tumble into a tiger den. Another storyline checks in on ne'er-do-well Francis, now the unlikely foreman of a dude ranch owned by a cheery German businessman.

Acting dumb like Reese eases Malcolm's stress and lands him a date with the new light of his life, an attractive girl who's really a dim bulb.

An academic competition faces the Krelboynes in an event Malcolm derides. Especially when he learns his teacher has a cheating plan. Also: a commitment to a formal dance ruffles Reese, who's now trying to ditch his date.

When Reese realizes the Army is too much for him to handle, he deserts and dresses as an Afghani woman. But Lois is on a march to find him, and travels to Kabul to hunt him down. Meanwhile, Malcolm volunteers at a veterans hospital as a way to make up for his guilt of making Reese leave.