Malcolm's cushy babysitting job provides relief from the trailer the family's using while their house is being fumigated, until Malcolm learns that the trust placed in him in his new position is strictly limited. Meanwhile, the military school's master key leads Francis to a corpse, for which he provides a proper send-off.

A relative's funeral conflicts with Malcolm's plans for his very first date, so he tries to figure out a way to skip the bereavement ceremony.

When the family goes to a water park for a day, Dewey is left home with an elderly, stern babysitter. Francis is hustled at pocket billiards by his military-school commandant.

Malcolm gets a role in the high school play and is so captivated by high school gossip that he forgets his lines. Lois discovers the joys of massage. Hal and Dewey build a society of model buildings in the living room. Francis tries to show his individualism at school when the commandant cracks down on personal belongings.

New neighbors, who turn out to be even more awful than Malcolm's family, move in next door; the Marlin Academy cadets prepare for a visit from Oliver North.

A hospital stay unsettles Malcolm, who's stuck in a kids ward with what may be appendicitis. Meanwhile, at military school, Francis leads a hunger strike.

When Malcolm and his brothers destroy their Christmas tree ornaments, Lois punishes them by canceling Christmas and moves all the presents into the garage. The only way she will reinstate the holiday is if the boys behave impeccably up to Christmas morning. Her plan works better than expected, and Lois is touched that her family responded so well to her challenge. Meanwhile, the boys decide that Lois could use this tactic for future holidays and retaliate by breaking into the garage and opening up all the presents. Elsewhere, Francis is forced to visit his Grandma Ida for Christmas.

The return of the smart and sassy Cynthia rattles Malcolm, who's astonished by her physical maturation. And so is drooling Reese.

Brotherly love is lost on Malcolm and Reese, now out to sabotage his sibling's birthday in devilish strikes met with crafty counterattacks.

A garage sale that's entrusted to Reese (yikes!) yields treasures near and dear, like Hal's old radio transmitter, which he makes operational. And a PC dating back to 1976 that Malcolm plans to sell to Craig for $1300.

Hal and Lois are penning their will, and think back to all the trouble their sons put them through. It is there that Lois' problems with Francis are finally revealed and how her inability to admit when she is wrong lead to a lot of the problems the family has been dealing with.

Malcolm gets a job working for Lois on the drugstore loading dock but is shocked to find that Lois smokes. She makes him promise not to tell, then turns her back on him and writes him up for a silly offense. Meanwhile, Dewey runs away to the Ranch to be with Francis because he says he is tired of Reese and Malcolm. Hal is also busy, secretly betting on and entering Jaime in baby competitions.

Malcolm convinces Dewey to do poorly on an I.Q. test, so that he won't become a ridiculed Krelboyne student. But Dewey does so badly that he is placed in a class for the emotionally disturbed. Hal and Craig compete in a dance competition.