Etienne walks outside his house, and feels strong and happy. Although what he’s doing will be dangerous, it will help his friends and allies. Etienne walks through the streets, preparing to calculate the locations of the German guns. As he walks, a “man in uniform” limps toward him.
Sometimes, Doerr’s chapter titles preempt or explain the events of the chapter: in this situation, for example, Etienne isn’t actually arrested, but the title delivers the main plot point (like the chapter “The Death of Walter Bernd”). It’s implied that von Rumpel is the one arresting Etienne—as he knows the house and is hoping to get the diamond—but it could be any other limping Nazi officer as well.