Description

Henry, Jessie, Violet, and Benny are four recently orphaned siblings (in the 1924 version of the tale, the children are orphaned in the first few pages; in the heavily revised and simplified 1942 revision, they have evidently been orphaned for some time). Not wishing to live with their hard-hearted grandfather, whom they have never met because of his disapproval of their parents' marriage, the children strike out on their own. On a cold night, the children stop at a bakery to ask for food. They are invited to stay the night, but while there, the children overhear the baker and his wife discussing a plan to keep the older children as labor while sending young Benny to an orphanage (in the 1924 version, they plan to send the children to their grandfather). The children escape and flee to the woods.

There they find an abandoned boxcar and renovate it into their new home. They find useful items such as kitchenware at the junkyard, use a stream for water, and collect blueberries for their meals. Realizing they cannot live on water and blueberries, Henry walks to a nearby town called Silver City for work. There he meets a young doctor, Dr. Moore, who hires Henry for odd jobs, often paying him in spare food and clothing as well as money. Suspecting that Henry is not telling the full truth about himself, Dr. Moore follows Henry home in secret and sees the children's living conditions. He decides that they are safe for now and that he should allow Henry to tell the truth when he feels comfortable. However, when Violet falls seriously ill, the doctor intervenes. He takes her to his own home to recover and invites the other children to stay there as guests.

Meanwhile, the children's grandfather, a wealthy steel baron named James Henry Alden, has been offering a reward for news of his missing grandchildren. The doctor connects the missing grandchildren with the ones in his care and goes to speak to Alden, warning him that his grandchildren are afraid of him and encouraging him to befriend the children before revealing who he is. Alden is introduced to the children as a friend of the doctor's. The children find him warm and friendly, so that by the time they learn the truth, they are surprised to learn that he is really their "cruel" grandfather and are more than willing to come live with him.

At their grandfather's house, the children are happy and well-cared for, but speak fondly of their days in the boxcar. As a surprise, Alden arranges to have the boxcar completely restored, repainted, and moved into his backyard where the children can visit it whenever they like.