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.

The film mainly follows the famous 1597 Battle of Myeongryang during the Japanese invasion of Korea (1592-1598), where the iconic Joseon admiral Yi Sun-sin managed to destroy a total of 133 Japanese warships with only 13 ships remaining in his command. The battle, which took place in the Myeongryang Strait off the southwest coast of the Korean Peninsula, is considered one of the greatest victories of Yi.