"Lump sugar" is the first domestic film that features a dynamic horse race, and its main theme _ a friendship between a female jockey and her horse _ seems to promise a touching story. Directed by Lee Hwan-gyeong and starring actress Im Soo-jeong, the film revolves around Si-eun (played by Lim), who dreams of becoming a famous jockey.

"When I first saw you, you were a little girl wearing a violet in your hair?"

As this lyric of "Violet" sung by Cho Dong-jin goes, a horse saw a girl and the girl saw the horse. The horse was the other self of the girl. They grew up together. "Lump sugar", is the first Korean movie to show the friendship between a human and a horse. The movie is a Korean-style horse movie, which is typically Hollywood material.

Si-eun (Im Soo-jeong) who was born at a ranch in Jeju Island, had a special friendship with a horse named Janggun (or "General" in English). Janggun died when she gave birth to Cheondung (or "Thunder" in English), who grows up with Si-eun like real brother and sister. Lump sugar is the horse's favorite snack and a special medium of love between them. Since Cheondung is sold abroad, they are separated. Two years later, Si-eun, who hopes to become a jockey, meets Cheondung again.

She loves a horse named Changgun, but it dies while giving birth. As she lives with a single father, she feels sympathy for the foal and she takes a good care of her, naming her Chundung, which means thunder in Korean. But her father doesn't want his daughter to become a jockey and sells Chundung without telling her.

Two years pass and Si-eun becomes a jockey, but she experiences discrimination because she is a woman. One day, she encounters Chundung on a street where she pulls a wagon to promote a dance club