It's the time of the Great Depression in America and businessman Charles Howard (JEFF BRIDGES) is trying to rebuild his life following tragedy in his family. While in Tijuana, he meets and falls for Marcela Zabala (ELIZABETH BANKS) and makes her his second wife. Following their marriage, they set out to buy a racehorse and employ the aid of former cowboy Tom Smith (CHRIS COOPER) to find a winner.
A man who has a way with horses, Tom picks Seabiscuit, a reportedly washed up and apparently troublesome three-year-old that never lived up to the champion heritage in his blood. He also chooses Johnny "Red" Pollard (TOBY MAGUIRE), a well-educated but unsuccessful boxer and jockey who's too small for the former but too big for the latter. Tom sees a kindred spirit in Johnny and Seabiscuit and quickly pares them together.
They soon start winning races, drawing the attention of flamboyant track announcer "Tick-Tock" McGlaughlin (WILLIAM H. MACY). Ever the salesman, Charles uses that to his advantage, as he wants his horse to take on War Admiral, the best thoroughbred out there. Yet, his owner, Samuel Riddle (EDDIE JONES), wants no part of the challenge. From that point on and despite facing adversity and various obstacles, Seabiscuit and the three men who handle him try for second chances in their lives, all while capturing the hearts and minds of the downtrodden American public.