after overhearing connie reporting her as an abandoned child, natty runs away to find her father on her own, embarking on a cross-country journey riding the rails along with other penniless travelers and hobos. along the way she saves a wolfdog from a dog fighting ring. in return the dog, whom she calls wolf, becomes her friend and protector in her attempt to return to her father. she has a brief, innocent romance with another young traveler, harry, and encounters various obstacles that test her courage, perseverance, and ingenuity, such as being arrested after cattle rustling and remanded to a juvenile facility. natty manages to escape the detention center and confronts the blacksmith who has been given control of the captured wolf. the blacksmith turns out to be kind and fair-minded; he releases wolf to natty, and gives her food, a ride to a train station and enough money for a ticket. she is cheated of her ticket money by an unscrupulous ticket agent, and narrowly escapes his attempt to turn her in, returning to "riding the rails" illicitly on freight trains, where she is unexpectedly reunited with harry in a rail-side shantytown.