Tells the story of Roberta (Bobbie), Peter, and Phyllis, whose lives are upended when their father mysteriously disappears one evening and the family is forced to leave their comfortable London home. They move to a modest country cottage where their mother supports them by writing books.
 
Near their new home, a railway becomes a source of wonder and comfort. The children wave daily to the “Old Gentleman” aboard the train and befriend the kind station porter, Perks, through whom they learn much about the world