In the story, we learn that Bronia, Ruth, and Jan are hesitant about setting out for Switzerland without Edek. So, the three children decide to look for him.
Upon their arrival in Posen, they head to a barracks by a river. There, a doctor tells Ruth that he sent Edek back to the Warthe camp the day before. Since the camp is only a mile down the river, the three children head there.
At the Warthe camp, the three discover to their dismay that Edek has escaped. An official describes Edek as a "wild boy" who ran away that morning. Since the camp doesn't have the resources to look for Edek, the children must look for him themselves.
The following day, they head to the village of Kolina, which is north of Posen. Rumor has it that a Russian field kitchen has been set up there to feed war-time refugees. The three children head to Kolina, partly from hunger and partly from a sense of helplessness. With Edek missing, they are hesitant to set out for Switzerland.
It is at Kolina that the three children find Edek. In chapter 13, we learn of a conversation between a doctor and Mrs. Borowicz (a welfare officer) at Posen. The doctor had wanted Edek to return to Warthe. He insisted that Edek looked ill and was much too thin to travel.
According to the doctor, Edek needed "fattening up." The doctor was afraid that Edek would die if he attempted to make the journey to Switzerland. However, the children manage to persuade the authorities to let them go. It is their deep resolve that convinces Mrs. Borowicz.