The Box-Car Children (Version 2) - Gertrude Chandler Warner

Henry, Jess, Violet, and Benny just lost their father and are all alone. To avoid being sent to the grandfather they fear, they have no choice but to run away. What follows is a weary midnight journey and the fun of settling into an old, abandoned boxcar in the woods. When Henry's job makes them new friends, they don't realize how important that will be for their future. - Summary by HannahMary