“Half-Broke Horses,” by Jeannette Walls, is just as enthralling as her memoir, “The Glass Castle.”

This time she relates the story of her grandmother by writing a “true-life novel.” Ms. Walls’s grandmother, Lily, was a survivor in her own time, just as Jeanette has been. Lily grew up on a poor farm, running free and loving every minute of it. She was fierce and strong and determined.

She broke horses and learned how to fall. She had little access to schooling but learned enough to become, at one point in her life, a teacher. Once, during a flash flood, she gathered her two younger siblings and the three climbed a cottonwood tree, where they hung on, clutching the trunk and branches for 24 hours straight. By her own iron will, Lily made sure that none of them fell asleep and fell out of that tree.

Growing toward adulthood, Lily took every kind of job she could find. During the Great War she was able to get herself hired as a teacher, even though she had only an eighth-grade education. She rode her pony more than 500 miles just to get
to the job.

Eventually she married and had two children. Rosemary (Rose Mary in “The Glass Castle”) was the older, the mother of Jeannette. A good teacher, Lily was determined to teach Rosemary, too – not just about math and reading, but about life. Rosemary, though, tough and determined as her mother, wanted to do things her own way. Where Lily was always planning for the future and saving her money, Rosemary was living each day to the fullest.

They battled.

As a young woman Lily had gone to Chicago, planning to get an education but realizing she might have to work as a cleaning lady while she studied. Lily always had a goal and believed that no door closed without a door opening. “You just had to find it,” said Lily. That was her motto.

Rosemary wanted to run free just as her mother had done. Nor did she want any animal to be cooped up in a pen. She, too, knew how to fall off a horse and then get back on. She was not a quitter. But she liked to paint and explore and laugh and have fun a whole lot better than sitting in a school room.

Even though this is the story of Lily, it is also the story of how Rosemary becomes the memorable mother in “The Glass Castle.”