Also Known As: Gu Family Book, Gu Family Secret
Genre: Fantasy, Period, Melodrama
Broadcast Network: MBC
Broadcast Period: April 8, 2013 - June 25, 2013
Air Time: Monday & Tuesday 21:55 KST (starting from April 15, 2013; Gu Family Book airs every Mondays & Tuesdays 22:00KST)
Director: Shin Woo Chul (A Gentleman Dignity, Secret Garden, City Hall)
Writer: Kang Eun Kyung (Man of Honor, King of Baking, Kim Tak Goo, Dalja Spring)
Official Website: gufamilybook
Cho Gwan Woong (Lee Sung Jae) who was born the lowest of class and was looked down upon by the people, managed to turn his desperate life around after getting first place in the military scholar exams. Blinded by his ambitions and greed for power, he caused the death of Minister Yoon and brought downfall to the Yoon family when he falsely accused them of treason.
Yoon Seo Hwa (Lee Yeon Hee) who was sold as a gisaeng to Chun Hwa Gwan, escapes with the help of Chun Soo Ryun (Jung Hye Young) and her maid (Kim Bo Mi) when she learns that her enemy, Gwan Woong has his eyes on her.
Seo Hwa & the guardian god of Jiri mountains, Gu Wal Ryung (Choi Jin Hyuk) met and fell in love when she ran to hide out in the mountains but Gwan Woong soon catches wind of her whereabouts and comes hunting for her once again. Feeling unable to raise her son while escaping along with the fact that Wal Ryung has disappeared as well, she sent him down the river in basket hoping that someone could take him in. Meanwhile, Wal Ryung who has lost all his memories began to serve under his enemies as their underling. The only thing that will make the normally amnesiac expressionless Wal Ryung goes in frenzy is whenever he gets to hear Seo Hwa's name.
Choi Kang Chi (Lee Seung Gi) who grew up with the Park family after he was picked up from river by Park Moo Sol (Uhm HoSub), the father of Park Kyung Jo (Lee Yoo Bi) and Park Tae Soo (Yoon Yeon Seok). Although Park Tae Soo used to treat him like a brother when they were younger, he started to feel a strong hatred towards Kang Chi when he misunderstood that Kang Chi is the main cause of the downfall of his family while Park Kyung Jo who always looked on him began to make use of Kang Chi to pave her way back to the noble status that her family once held after she was sold as a gisaeng to Chun Hwa Gwan and fate leads Kang Chi to meet up with Chun Soo Ryun, the head Gisaeng twenty years later after she encountered his mother.
Dam Yeo Wool (Bae Suzy), the daughter of Kang Chi and Tae Soo's teacher is one of the instructors of the martial arts school and despite her young age, Yeo Wool is highly skilled in archery. Although the cross-dressing Yeo Wool is always clashing with Kang Chi because of their different personalities, they find themselves falling for each other as they got to know each other better.
Kang Chi soon discovers that he is actually a half-man and half-beast when his special abilities began to show after he goes after some criminals and to become a full human, he needs to find the Gu family's book to find the way to become one. When Kang Chi sets off on journey to seek his humanity, he ended up confronting his greatest enemy of his life, his father who never aged nor knew about his existence.
Lee Seung Gi as Choi Kang Chi
His father is Goo Weol Ryeong (Gu Wol Ryung), a guardian spirit of Mt. Jiri and his mother is Seo Hwa, making him a half-human and half-animal. Unbeknownst that he was born half-human and half-animal, he is abandoned by his mother who left him floating in a basket in a river. He is found by merchant Park Mu-sol who runs the Baeknyeongaekgwan. Kang-chi is impulsive, reactionary, and uses physical force before thinking twice. He starts life anew after encountering Dam Yeo Wool and Yi Sun Shin.
Bae Suzy as Dam Yeo Wool
She joins her father who was tasked with the job of investigating a series of murders by Yi Sun Shin. She crosses paths with Kang Chi who is falsely accused of committing murder. While Kang Chi always caused trouble, Yeo Wool discovers his innermost secret. This makes her feel sympathy for him. Even after knowing the truth that Kang Chi is half-human and half-animal, she trusts that he will not harm people and stands by his side. She is the only person who can calm down Kang Chi when he goes on a rampage.
Yoo Dong Geun as Yi Sun Shin
After being appointed as governor of Jeolla Province by Yoo Seong Ryong, he was the first official to detect the presence of Japanese spies in the Joseon kingdom. After learning that Won Gyun controls the royal palace and all the key royal administrations, he asks Dam Pyeong Jun, who oversaw a secret army of men, to spy on Japanese spies. One day, he encounters a strange boy called Kang Chi. Although Kang-chi appears to be a human, Yi Sun-shin discovers that there is another power that lies within him. So he puts Kang-chi under the charge of Dam Pyeong-jun, asking him to lead the boy towards a right path. Whenever Kang-chi is in a perilous situation, Lee Sun-shin will appear to show him a meaningful lesson to learn from the situation. He is Kang Chi's eternal mentor and hero.