Young and free Laurie has recently started kindergarten, and his mother (who also narrates the story) laments that her "sweet-voiced nursery-school tot" is growing up. She also notes changes in his behavior: he no longer waves goodbye to her, slams the door when he comes home and speaks insolently to his father.
During lunchtime conversations, Laurie begins telling his parents stories about an ill-behaved boy in his class named Charles, who yells and hits his teacher and classmates. Though in a way fascinated by the strange boy, Laurie's mother wonders if Charles' bad influence is responsible for Laurie misbehaving.
Over the ensuing weeks Charles seems to be going from bad to worse until one day at the beginning of the week Laurie tells his parents that Charles behaved himself and that the teacher made him her helper. By the end of the week, however, Charles reverts to his old self when he makes a girl in his class repeat a bad word to the teacher. The next school day, Charles mumbles the word several times to himself and throws chalk. Laurie also says that he misbehaves quite often.
When the next PTA meeting rolls around, Laurie's mother is determined to meet Charles' mother. She closely examines the other parents and sees nothing but pleasant faces and is surprised when Charles is not mentioned at all. After the meeting, she approaches the teacher and introduces herself as Laurie's mother. The teacher says that once Laurie adjusted he became "a fine little helper. With occasional lapses, of course." Laurie's mother then mentions Charles and the teacher tells her that there is no one named Charles in the class. (The story thus implies that all the trouble has been caused by Laurie.)