The story begins with the narrator, a young boy, walking to his first day of school. He is excited about his new clothes for the occasion but feels uneasy about attending school. As he holds his father's hand, he occasionally asks why he must go, feeling as though he might be sent away from home as a form of punishment.

Despite his father's reassurances, the boy remains unconvinced that "there really was any good to be had in tearing me away from the intimacy of my home." At the school gate, he hesitates again and needs a gentle push from his father to enter the schoolyard. His father tells him to "be a man" and explains that "today you truly begin life."

Upon entering the yard, the boy sees the faces of other children but feels "like a stranger who had lost his way." Another boy approaches and asks who brought him to school; when he replies that it was his father, the boy reveals that his own father is dead.

The narrator soon integrates into the group of children, and the narrative voice shifts from the first person singular "I" to the third person plural "we."

He befriends some of the boys and falls in love with some of the girls. He describes the school day as an allegory for human life, with its ups and downs, trials, and tribulations.

When the bell rings to signal the end of the day, the narrator steps outside the gate but finds his father is not there as promised. He meets a familiar middle-aged man; they greet each other and shake hands before the man moves on.

The narrator notices that the street and surroundings have completely changed since the morning. These changes symbolize the impact of modernization and urbanization, radically transforming the city within one man's lifetime.

He struggles to cross the street due to heavy traffic. Finally, a "young lad" offers to help him across, addressing him as "Grandpa." The young boy has lived an entire lifetime in what seemed like only half a day and is now an old man at the end of his life.