Tommy Sands lives with his mother on a dead-end slum street in London. Shortly after giving birth to Tommy's sister, Elspeth, their mother died, and the children are moved to Thrums, Scottland, where their mother had lived before. In Thrums, they are taken in by a man Tommy's mother had refused, many years ago. In the harsh London slum, and then in the difficult world of Thrums, Tommy's imagination make it possible for him to survive without bitterness, and to care for and encourage his sister.