Seabiscuit is as much a story about 3 men as it is a story about a horse. The owner, the trainer, and the jockey were each principled men who believed in each other and in Seabiscuit. This late-blooming horse from the west coast (most of the horse-racing action was on the east coast) never won in any of the "Triple Crown" races, since those are only for three-year-olds. He was already older than that when the trainer told the owner that he could make something out of the gangly horse.
Through telling the story of the horse and the 3 men, the author also tells a story of life at the racetrack and life during the depression. Plenty of interesting details are given about the strategy of the racetrack, such as the weights the horses must carry (determined by a judge), how to convince a lazy horse to train adequately, early leaders vs. endurance runners, bookmakers and odds, etc. Also, the daily lives of the trainers and jockeys are described, oftentimes sleeping in the stall with the horse (and possibly other animals such as goats and dogs to keep the horses company). The ordeals that the jockeys went through to "make weight" are described in gruesome detail; many of them started in the job as adolescents and tried to remain small enough to ride even as they grew. The dangers that the jockeys faced on the job are apparent, as Seabiscuit's jockey is seriously injured multiple times.
Even though I had never heard of Seabiscuit, he truly was a legend in his own day. Everyone was talking about a race between Seabiscuit and War Admiral, the biggest star on the east coast race circuit, and everybody had a favorite. During 1938, there were more newspaper column inches written about Seabiscuit than about any other public figure (FDR was second and Hitler was third in popularity). Quite a claim to fame for a horse!
In summary, this book is a great example of how to write a nonfiction book. There are sufficient notes to make it authoratative, but they don't distract from the story. The writing is outstanding, and the story is interesting. As the author notes, "history hides in curious places," including at the racetrack. The book is highly recommended for anybody with a curious mind and an interest in history.