After several weeks at Out-With, Bruno concludes that he had better find a way to keep himself occupied or he will surely lose his mind. One Saturday, when neither Mother nor Father is at home, he decides to make a swing in a large oak tree a good distance from the house. For this project, Bruno will need a rope and a tire. He finds some rope in the basement of the house, but to secure a tire, he will have to ask Lieutenant Kotler.

Lieutenant Kotler is the soldier Bruno encountered on his first day at Out-With. The young man has been seen frequently around the house since that time, coming in and out “as if he owned the place.” Bruno dislikes the lieutenant, although he does not fully understand his own feeling, but as there is no one else to ask about a tire, he sets out to find him.

On most days, Lieutenant Kotler is dressed sharply in his carefully pressed uniform, but today, Bruno finds him outside the house in street clothes, deep in conversation with Gretel, who is “laughing loudly and twirling her hair around her fingers” as she interacts with the young man. Bruno is instinctively disgusted with his sister’s flirtatiousness. Wanting to take his leave as quickly as possible, he states his business directly, politely asking the lieutenant if he knows where he can find a spare tire.

The lieutenant responds by making a joke Bruno does not understand. Gretel, irritated by her brother’s interruption, tells the lieutenant, whom she addresses as Kurt, that he must excuse Bruno’s stupidity, as he is only nine. Bruno snaps back that Gretel is only twelve and shouldn’t be pretending to be older than she is, embarrassing her in front of the lieutenant.

Lieutenant Kotler finally arranges to get Bruno the materials he needs, rudely ordering Pavel, an old man who prepares and serves the evening meal for the family each day, to take the boy to the storage shed and fetch him a tire. The harshness with which the he addresses Pavel makes Bruno feel ashamed. When Bruno gets his tire, he goes to the tree and spends the bulk of the afternoon constructing a swing. When he is done, he lies flat across its center, using his feet to push himself higher and higher.

When the swing is at a particularly high point, Bruno loses his grip on the tire and plunges to the ground. When he rises, he discovers that he has sustained quite a wide gash on his knee. Fortuitously, Pavel comes out of the house and carries him back into the kitchen. The old man expertly cleans the wound on Bruno’s knee and covers it with a bandage. Bruno thanks Pavel and suggests that when his mother sees his injury, she might want to take him to the doctor, but Pavel tells him that the gash is minor and that there will be no need. Irritated, Bruno demands, “Well, how do you know . . . you’re not a doctor.” To his surprise, Pavel replies quietly, “Yes I am.” Bruno is confused and asks Pavel how he can be a doctor when he only peels vegetables and waits on tables. The old man responds that he practiced medicine before coming to Out-With. Before he can explain further, Mother returns, and Pavel does not speak to Bruno again.

When Mother hears from Bruno what has happened, she looks “distinctly uncomfortable” and sends him to his room. As he leaves, Bruno hears his mother thank Pavel and tell him that should the Commandant ask about the incident, they should say she was the one who cared for Bruno’s injury. Bruno is surprised at his mother, thinking she is being very selfish for taking credit for something she had not done.