Under the influence of the Yuan Kingdom, the King of Goryeo (Joo Jin-Mo) is pressured to produce a successor to the throne, but the king is in love with his loyal general Hong-Lim (Zo In-Sung). The King then asks his lover Hong-Lim to sleep with the Queen (Song Ji-Hyo), with unexpected consequences.
The Goryeo King (Joo Jin-mo) is married to a Yuan Dynasty princess (Song Ji-hyo), but they do not have any children. There is constant pressure on the King both from the Yuan emperor and the Goryeo Kingdom to produce a crown prince and ensure the continuity of its royal dynasty. The King's palace guard is composed of thirty six young soldiers, led by military commander Hong-rim (Jo In-sung) who is also the King's lover. The King finally decides to charge Hong-rim, with a strange commission: make love to the Queen and beget a child. Hong-rim and the Queen are uncomfortable accepting the royal order, but they finally comply. However, their relationship does not stop at procreation, but a true love blossoms between the two, and in this intimate relationship there is no place for the King.
The two lovers surpass their "official mission" and continue to meet each other at midnight in the library. The King begins to suspect Hong-rim's infidelity and soon gains evidence through another subordinate. To punish them and to also gauge the depth of Hong-rim's affection for the Queen, the King brings the two together to his chamber. The king tells them that he has decided that the Queen's "consummation" for an heir will continue, but only with another subordinate. The king remains firm in his decision despite entreaties from both the Queen and Hong-rim.
In despair, the Queen attempts to kill herself by slitting her wrists but fails. In a last-ditch effort to change the King's mind, Hong-rim asks the Queen to stay away from him and goes to the King to offer his own life in exchange for forgiveness. The King pardons him after hearing that Hong-rim's involvement with the Queen was purely lust. He decides to overlook everything that had happened and instead sends Hong-rim away for a while to have him clear his mind and settle his emotions.
The night before Hong-rim's departure, the Queen's personal maid secretly informs him that the Queen wishes to meet him for one last time. She also bears news that the Queen has finally conceived. Hong-rim sneaks out of the King's bedside to meet the Queen in the library. They end up making love in the library, and the King catches them in flagrante delicto. When the two lovers attempt to save the other by begging the King to "kill me instead," the King realizes how strong their love for each other is. In a fit of jealousy, he has Hong-rim castrated and sent to prison. The Queen finds a way for Hong-rim to escape with the aid of Hong-rim's closest subordinates.
Upon finding that Hong-rim has escaped, the King demands to know where he is from the Queen, who refuses to answer. In response, he kills her personal maid. The King is aware that the Queen is with child and by this time, everyone who knows that the Queen's child is not the King's, is exterminated.
Meanwhile Hong-rim, upon realizing that the Queen is still in the palace and not on the run as his subordinates told him in order to quickly escape, heads towards the palace on horseback despite his subordinate's protests. He stops in his journey when he realizes how futile it would be, and returns to the refuge where his subordinates took him to but find that they have been captured.
At the palace, the King tortures the subordinates to find the whereabouts of Hong-rim, and when they remain silent, beheads them. Their heads are put up on posts on the palace gates along with the Queen's personal maid. But the female head is wearing the Queen's necklace in order to lead Hong-rim to believe the queen was also killed and return to enact revenge. When Hong-rim sees this, he is indeed enraged and goes to the King to kill him. An intense sword fight ensues. However, the King manages to stab Hong-rim in the shoulder, and while he is pinned, he asks Hong-rim a last question: whether or not Hong-rim had ever felt real love for the King. Hong-rim replies that he had never felt love for him. Hearing his response, the King is shocked, giving Hong-rim time to throw a lethal stab of his own sword through the King. One of the royal guards, having watched part of the battle, now intervenes by fatally stabbing Hong-rim. The Queen comes upon the scene with the guards at her heels, trying to hold her back. She calls out for Hong-rim. After she is taken away out of sight by the guards, he turns his head from her direction and faces the dead king, realizing that the king had not killed her after all. He dies facing the king, his eyes filled with question at the King's fruitless test.
The last few seconds of the film show a flashback to when the King showed young Hong-rim the view of the city and asked if Hong-rim wished to live together, to which the young Hong-rim replied yes. The film ends on a montage of the King and Hong-rim happily hunting together, reckoning back to a dream the King once had.
