A historical drama set in the Koryo dynasty and focused on the relationship between a king and his bodyguard. Under the dominance of Yuan Dynasty China, the king of Goryeo Dynasty Korea is pressured to produce a successor to the throne. Unable to make love to his queen because he is in love with his bodyguard, Hong Lim, the king asks the two of them to sleep together instead. This sexual contact formulates a forbidden love between Hong Lim and the Queen.

During the confusing and conspiratorial Joseon Dynasty King Gwang-hae orders his councilor, HEO Kyun, to find him a double in order to avoid the constant threat of assassination. HEO Kyun finds Ha-sun, a jester who looks remarkably like the king, and just as feared, Gwang-hae is poisoned. HEO Kyun proposes Ha-sun fill the role as the king until 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 Gwang-hae, Ha-sun’s affection and appreciation of even the most minor servants slowly changes morale in the castle for the better. However, his chief opposition, PARK, notices the sudden shift in the king’s behavior and starts to ask questions.