"Grand Prix" covers the world of horse racing, centered around the romance between a male horse jockey and a female horse jockey.Seo Joo-Hee (Kim Tae-Hee) is an ambitious equestrian who loses her beloved horse in a racing accident and also injures her arm. Devastated she quits the sport and travels to Jeju Island. On Jeju Island, Seo Joo-Hee meets fellow equestrian Woo-Seok (Yang Dong-Kun), a former winner of the Japan Cup who is also experienced a similar slump as Seo Joo-Hee. With Woo-Seok's help, Seo Joo-Hee becomes inspired to compete for the Grand Prix Chamionship.
Hee-soo has been a bestselling author for the past 20 years. But her reputation and fame are all butchered overnight when she is accused of plagiarizing a competition entry that she juried. She falls into despair for 2 years, but with the help of her long-time friend publisher, she dreams of a spectacular comeback. She drives to a remote pension deep in a small town with her daughter Yun-hee. At this quiet and uncanny pension, Yun-hee begins talking to an unidentified figure. Dying for a new source of inspiration, Hee-soo turns the stories that Yun-hee hears from this figure into her new book, which turns into a bestseller. But her regained fame doesn’t last long as she is again accused of plagiarizing a novel that was published 10 years ago. In order to prove her innocence, Hee-soo begins a mysterious journey to expose the truth.