After his oldest brother is sent to military camp, Malcolm, a child genius, is left in the middle between his two other brothers.
When Francis is left in charge of his brothers, mayhem ensues, and Malcolm gets hurt, requiring hospitalization.
Lois has a showdown with the other mothers at a Krelboyne picnic, while Reese preys upon Malcolm's gifted classmates.
Exasperated with nonstop complaints, Lois throws in the towel, which leads to the rapid breakdown of family life.
Chaos ensues when Malcolm invites his Krelboyne classmates over to his house to build a robot for a competition.