The Concubine (2012)

Cast
Jo Yeo-jeong (조여정) as Hwa-yeon (화연)
Kim Dong-wuk (김동욱) as Prince Seong-won (성원대군)
Kim Min-joon (김민준) as Kwon-yoo (권유)
Park Ji-yeong (박지영) as Dae-bi (대비)
Jo Eun-ji (조은지) as Geum-ok (금옥)
Lee Kyeong-yeong (이경영) as Eunuch (내시감)
Park Cheol-min (박철민) as Pharmacy eunuch (약방내시)
Ahn Seok-hwan (안석환) as Sin Cham-pan (신참판)

Also known as "Royal Concubine"

Trailer
http://youtu.be/FYRtx7UMm2I

Synopsis
Movie depicts a tragic love triangle story between Hwa-Yeon (Jo Yeo-Jeong), her true love Kwon-Yoo (Kim Min-Jun ) and the man who will be King (Kim Dong-Wook).
Prince Sungwon (Kim Dong-Wook) sees Hwa-Yeon (Jo Yeo-Jeong), the daughter of a wealthy nobleman, for the first time and falls in love, but Hwa-Yeon loves Kwon-Yoo (Kim Min-Jun). Kwon-Yoo saved her father's life and now lives with her family.
Meanwhile, Prince Sungwon's mother (Park Ji-Young) notices her son's infatuation with Hwa-Yeon, but she doesn't think Hwa-Yeon is good enough for her son. Prince Sungson's mother then schemes to have Hwa-Yeon become the concubine to her stepson the King (Jung Chan). Hwa-Yeon and her true love Kwon-Yoo run away when they learn of this plan, but are soon captured by her father's men. In order to save Kwon-Yoo's life, Hwa-Yeon agrees to become the King's Concubine.
Hwa-Yeon gives birth to a son a little bit less than a year later. She will then become a Queen. Several years later, the King becomes sick and dies suddenly. Prince Sungwon becomes the King, but his mother now wields true power. Hwa-Yeon then learns that the King's stepmother had the King killed to put Prince Sungwon on the throne. Hwa-Yeon also realizes that to survive in the royal palace and protect her own son, she will have to change.
King Sungwon is now agonized over his desires for his deceased brother's wife Hwa-Yeon and his mother's domineering ways. One day, Hwa-Yeon sees her true love Kwon-Yoo in the palace and he has now become an Eunuch.