Henry, Jessie, Violet and Benny search for a place to call home after their parents die. Although they do have a grandfather that they have never met, they are determined not to let him find them. They think he is mean and cruel because he did not approve of their father’s marriage to their mother. Jessie finds a deserted boxcar in the woods near Silver City, and the children make it into their home. While Henry finds work doing chores for Dr. Moore and his mother, Mrs. Moore, Jessie, Violet, and Benny find dishes and other necessities in the town dump. They also find a stray dog that they name Watch.
Unbeknownst to the children, who make a fireplace and a swimming pool in their free time, the Moores keep an eye on them. They like Henry and want to make sure he is safe. Before long, Dr. Moore realizes that the children’s grandfather is a rich, kind man who lives not too far away, Mr. James Henry Alden. When Mr. Alden holds a Field Day for Silver City, Dr. Moore asks Henry to go to it. Henry ends up winning the Free-for-all Race and shaking his grandfather’s hand as he accepts the prize. Yet neither Henry nor Mr. Alden know they have met a relative.
When Violet becomes sick, Henry asks Dr. Moore for help. Dr. Moore brings Violet and the other children to live at his house until Violet feels better. He reveals the children’s identity to Mr. Alden. Mr. Alden does not tell the children who he is, but lets them get to know him. By the time they realize that he is their grandfather, they also know him as a kind man.
The children go to live with their grandfather, who has designed special bedrooms for them and tries to make them feel at home in his large house. To help them fully adjust, he moves their boxcar to one of his gardens so they can play in it whenever they like.