The confusing and conspiratorial 15th ruler of Korea's Joseon Dynasty King Gwanghaegun of Joseon (Lee Byung-hun) orders his secretary of defense, Heo Gyun (Ryu Seung-ryong), to find him a double in order to avoid the constant threat of assassination. In a constant fear of poisoned, the king get obnoxious and threats everyone around him, including the kitchen maids. Heo gyun finds Ha-sun, a lowly acrobat and bawdy joker who looks remarkably like the king to replace the king occasionally whenever the king is out of the palace. In few days, just as feared, King Gwang-hae is drugged with Poppy by his favourite consort, conpired by the Law minister. Heo Gyun proposes Ha-sun fill the role as the king until King Gwang-hae recovers fully and grooms Ha-sun to look and act every bit the king. While assuming the role of the king at his first official appearance, Ha-sun begins to ponder the intricacies of the problems debated in his court. Being fundamentally more humanitarian than King Gwang-hae, Ha-sun’s affection and appreciation of even the most minor servants slowly changes morale in the palace for the better. Over time he finds his voice and takes control of governing the country with real insight and fair judgments. Even Heo Gyun and the chief enuch moved by Ha-sun’s genuine concern for the people, and realizes he is an infinitely better ruler than Gwang-hae. Ha-sun even fight for the respect of the Queen's safety and protect her and her brother from death sentence. However, his chief opposition, Park Chung-seo (Kim Myung-gon), notices the sudden shift in the king’s behavior and starts to ask questions. The queen (Han Hyo-joo) is also conflicted between the real king and the fake king’s secret. The chief enuch and the secretary of defense ask Ha- sun to leave the country for good. The king was again brought back to the throne to punish the revolts.