When the novel opens, the three “railway children” of the novel’s title—Roberta (Bobbie), Peter, and Phyllis—are living privileged, upper-class lives with their parents in London. Their father works for the government; their mother is an artistic woman who loves to tell stories and writes poems to amuse her children. They live in a large house with servants, and “always had everything they needed: pretty clothes, good fires, a lovely nursery with heaps of toys, and a Mother Goose wallpaper” (6). This idyllic existence ends abruptly days after Peter’s birthday when two men show up at the house and have a heated conversation with Father, who disappears shortly afterward. Peter’s toy engine—his favorite birthday present—is left broken, as Father has not had time to fix it before his disappearance. Mother announces that Father will be away for a while and that the family must move to the countryside, admitting to the children that the family needs “to play at being poor for a bit” (24), although she doesn’t tell them why.

Upon their arrival in the countryside, the children discover that their circumstances have changed drastically. Their new house is modest and not as comfortable as their modern, spacious house back in London.