The family takes a day vacation at the water-park. All except Dewey, who has to stay home with an overage babysitter, which turns out to be more fun than expected. While Malcolm and Reese get into a loop of revenge-pranks, Hal and Lois try to enjoy the day off. As Dewey's babysitter hits the dance-floor, in more than one way, the youngest member of the family sets off on his own.

As the family drives home from the water-park, they get stuck in a traffic jam. While each family members tries to deal with heat, stress and boredom in their own way, Dewey is roaming the country on his own.

Commandant Spangler announces his mother's visit and Francis uses the opportunity to organize a dance, for which he invites some local girls, which ends up to be a very different experience then the cadets expected. Meanwhile the Kenarbans invite the whole family to a nice dinner that turns into an evening of conflicts, as the families get to know each other better.

The family is on a weekend-vacation in an native American casino. Francis uses this opportunity to go on vacation himself, by sneaking into his former home, but he is not the only one with that idea. While Hal, Reese and Malcolm get lost in the desert, Lois and Dewey enjoy a day of relaxation.

Hal and Lois heads off to a convention while the boys stays home for the babysitter. Malcolm, Reese and Dewey assumed it's just another old woman, their parents hired to watch them. They decide to do a series of pranks on their babysitter, which includes the covered up sewer tank with a blanket and a book for the old woman sit on. To their surprise, their babysitter is a hot, teen-aged girl named Patty. She is sweet to them, but also bitter because she was rejected by Francis, a long time ago, because she was obese. Now the boys compete against each other to see who will prove their eldest brother wrong in his rejection and sleep with her without sex. Meanwhile at the convention, Lois tries in vain to stop the fight between Hal and Jack, who stole his idea.

In an attempt to avoid the worst moments of medieval week at his Krelboyne class, Malcolm spins a delicate web of deception for the school therapist. Francis takes over the laundry at the academy and Hal discovers that his youngest, Dewey, is a natural at skittles.

Lois finds an amazing and cheap massage table at the grocery store and manages to become so relaxed that she doesn't even care about Hal and Dewey's LEGO city.

Reese, promising champion of his school's wrestling team, gets beaten by a girl, completely demoralizing him. So he gives up his school-bully carrier, which destabilizes the natural order of things at school. Francis tries to get out of academy at his birthday in an attempt to avoid academy-birthday-traditions.

Malcolm accidentally hits a ball into grouchy old Mrs. Griffin's yard, and when he goes to retrieve it, he has a run-in with the elderly lady that accidentally makes her fall and break her arm. As punishment, he must go over to her house every day after school to help her out. Meanwhile, Dewey begins to carry a purse to school instead of a backpack; and Francis must deal with his screw-up friend Richie at military school.

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. To make matters worse, Grandpa Victor gives Reese a live grenade as a present, and worse comes to worse, the boob pulls the pin! Luckily the family survived the explosion, but their brand new, expensive refrigerator wasn't as lucky.

When Lois is arrested for having 16 unpaid parking tickets, she makes Francis pay for them and fights the cop in court for falsely accusing her of something she never did.

In this episode Craig still lives in Lois and Hal's house, because his one had been burnt down. That costs a lot of things on the whole family. Meanwhile, Malcolm and his brothers find a mini-bike in the garbage. At first they argue with each other, but after their mother banned the use of the bike, they join forces against her. At the same time Hal goes to Allabama to visit his son Francis for the Fathers-and-Sons meeting, where he expects some great achievements from his son. But what will happen after all that ?