Unlike the recent South Korean period dramas, the movie has a notable anachronistic feeling. It seems its background is the Joseon dynasty(1392-1910) considering the design of architectures in the film, but there is also the influences from the Goryeo dynasty(918-1392) in the characters' costumes and other details. They behave like the people living during the Joseon dynasty, but, as far as I know, there was not any incident during that period which can possibly inspire the lurid story of the film, and I have never heard about the king's mother presiding over the copulation ritual of her son and daughter-in-law in the next room.
But, despite its fictional world, the ruthless pursuit of power in the palace is a familiar story you have encountered in other stories. The king is dead due to an unidentified cause, and the king's mother(Park Ji-yeong), who is actually his stepmother, now holds the power to decide who will be the next king. She quickly puts her own son, Prince Seong- won(Kim Dong-wuk), on the throne, and she also swiftly eliminates her opponents including the previous king's father-in-law.
In such a circumstance like that, the previous king's wife, Hwa-yeon(Cho Yeo-jeong), naturally has lots of worry about not only her future and but also her young son's future. He is just a child at present, but this innocent kid is already deemed as a potential threat to the kingship, and he can be killed at any time if the king's mother and her followers have a chance to get a good reason for that. Some of South Korean audiences have never heard of Lady MacBeth or Richard III, but they will be reminded of several bloody incidents during the Joseon dynasty or other dynasties preceding that. King Danjong of the Joseon dynasty was dethroned by his uncle, who became the next king, and then this young boy was killed later when he was thought to be too much of trouble(believe or not, it was said that this horrific decision was strongly supported by his great uncle). In case of Prince Young-Chang, he was murdered by King Gwanghaegun of the Joseon dynasty just because he was a more legitimate heir to the throne than the king himself. Anything could be committed for absolute power in those days, you know.
Unlike his ruthless mother, Prince Seong-won has other thoughts about his sister-in-law, and we know why. While he was merely a prince, he met her in her father's house, and he has been obsessed with her since then. His mother already sets him up with the other woman as his queen when he becomes the king, but he still wants Hwa-yeon in spite of his mother's warning. It may be not that bad to sleep with the deceased brother's wife(well, he is the king, isn't he?), but it can be fatal to sleep with someone who can threaten the power.
The situation becomes more complicated after another player of this dangerous game of palace intrigue appears in the palace. His name is Kwon-yoo(Kim Dong-wuk), who was Hwa-yeon's former lover in the past. When he tried to elope with Hwa-yeon before she was sent to the place as the previous king's new wife, he was captured and castrated by Hwa- yeon's father, and now he enters the palace as one of new eunuchs. While he is quickly promoted enough to be near the king, he becomes also a little closer to Hwa-yeon though he lacks a certain body part crucial for rekindling their feelings in the past. Can she trust him as a close ally? And does she really have some feelings for him as he guesses?
You never can be sure about them because of the understated but competent performances by Jo Yeo-jeong and Kim Min-joon. Revealing real feelings in the palace can be a fatal blow to your fate, and they must hide their emotions and thoughts as much as possible to survive. Jo Yeo- jeong is good as a woman who gradually becomes as ruthless and cunning as her enemies through her need to survive. When she comes to know that the king wants her, she see it as an opportunity to win the game, and she is determined to manipulate him to turn against her devious mother- in-law.
Meanwhile, clueless and reckless Guem-OK(Cho Eun-ji), a maid who has served for Hwa-yeon, finds herself in a serious situation way over her head. She is forced to copulate with the king when he is very frustrated over his desire toward Hwa-yeon, and we can say that she is virtually raped, but, what do you know, she feels a lot better to see her changed position as one of the king's concubines. Unfortunately, while intoxicated with her newly gained power, she does not have the slightest idea about how dangerous the power game can be between the women in the palace.
The king's mother is the most powerful and dangerous player in this perilous game, and Park Ji-young gives a juicy villainous performance which ably supplies grand gestures whenever they are required. The king's mother has probably done many terrible things for protecting his son and making the throne ready for him, but it is not easy for her to resist the power behind the throne – and now her dear son is becoming one of the major blocks in her grand plan.