Peter, Phyllis and Roberta's lives change overnight when their father is taken away by two strangers. They move from the comfort of their London home to a small country cottage, and are left to their own devices while their mother writes day and night to support the family. But with their new poverty comes more freedom than they ever dreamed of, and the railway line at the bottom of their garden offers the trio a world of new friendships that will change their lives forever.