Malcolm is the little genius of the family. And when you see the intellectual level of the rest of the family, he is REALLY a genius. Hal is the slightly irresponsible father who always gets confused in everything he does. Lois is the bossy mother, who runs her family as best she can. Francis is the older brother. A rebel, he is sent to military camp to try to restore some sanity to the young man's life. But he makes you see all the colors. Reese is the daredevil, stupid, violent and desperate for his family.
Dewey is the youngest of the family, he discovers the world with a very endearing first degree. He is very naive and sees the world differently.
Their great enemy is Ida, Lois' mother. She is a poison on each of her visits. Craig is Lois' colleague. He is secretly in love with her.
Malcolm is one of the light bulbs, a group of smart students who are a bit of a misfit at school. There is Stevie, Malcolm's best friend. Handicapped and asthmatic, he is perhaps the nicest of Malcolm's entourage.
In their daily life, a little can make the whole family machine jam as well as the children's biggest misdeeds. Even if Malcolm is intelligent, he is still a child who wants to test everything.
Hal has Abe as a friend. Together they are like two kids.
Mischief, love affairs, money problems, everything is a pretext for the family unit to help each other.