Told from the third-person omniscient point of view, the story begins by noting that “it” began 30 years ago. The “it” is magic, but before the magic begins, four siblings are introduced. Jane is the oldest and most authoritative. Mark is the only boy. Katharine is the middle girl, and Martha is the youngest and most challenging.

The children’s mother works for a newspaper, and their father has died; as a result, a woman named Miss Bick looks after them every day. The children long for an adventure in the countryside, but Miss Bick refuses to take them.

Despite this, the children still enjoy summer. They relish going to the library and reading. While all of them love fiction, Mark detests nonfiction because it tricks him into learning things. Katharine recites poetry on the walk home, much to Martha’s chagrin, who refuses to walk until Katharine stops. As a result, the kids make a rule that they cannot read out loud. However, once they discover the writer E. Nesbit, they make an exception.

When they borrow the last of Nesbit’s books, Jane reads it aloud all the way home, through dinner and into bedtime, picking up where she left off the next morning.