Malcolm has been labeled a boy genius and is moved, much to his chagrin, into the Krelboyne class, which is a class full of nerds and geniuses like himself.

Malcolm stays overnight at Stevie's house. He convinces Stevie to sneak out of the house with him and they go to an arcade downtown, but Stevie's wheelchair is stolen, and they have to team up to find his wheelchair while dragging Stevie in a cart. Meanwhile, to prove that he is mature, Lois challenges Reese to give Dewey a bath and put him to sleep in exchange for being allowed to stay up late to watch a scary movie, but the task proves more difficult than he expected, just as Lois thought it would. At the academy, Francis is hazed by a group of students, but tells them their tricks are amateurish to what Lois did to him, and the students decide to worship Lois.

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 boys and Stevie take off in the evening to visit the carnival but get into trouble, while the parents go searching for them.

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.

Kitty returns to the her family after leaving them. However, Lois refuses to accept her back in the neighborhood and refuses to talk to her.

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 boys and Stevie take off in the evening to visit the carnival but get into trouble, while the parents go searching for them.

Kitty returns to the her family after leaving them. However, Lois refuses to accept her back in the neighborhood and refuses to talk to her.