《代立军》讲述壬辰倭乱时，逃到了国外进行避难的宣祖执掌朝政的故事，彼时的王世子光海君，和一名替别人服兵役的士兵相遇。从此开始了一段故事。正在1592年，朝鲜壬辰的倭寇之乱爆发，宣祖让少年光海军承担分朝的责任。自己则前往宜州想要躲避战乱。彼时的光海在战乱之中召集起了一群老弱病残，并决定代替君主召集士卒，想要抗衡侵略，面对自己聚集起的这一群老弱病残，代立军的首长土雨表示自己将会带领下属们冲锋陷阵，以此保卫光海军的平安。

然而在土雨带领手下们突围时，他们突然遭到刺客的袭击，还有许多人想要抓走光海君，以此邀功请赏，面对日本军队的埋伏，代立军和王室之间开始了相互猜忌。他们谁也不知道是谁将日军引来的，也不知对方意欲何为，为了自己的生存，这些人开始了尔虞我诈。

"Dai Lijun" tells the story of King Seonjo who fled to a foreign country during the Imjin Japanese Invasion and took refuge in the government At that time, the prince's son Guang Haijun met a soldier who was serving in the military for others. And so began a story. In 1592, the Japanese pirate rebellion in Imjin, Joseon broke out, and Sunjo let the boy Guanghai bear the responsibility of dividing the dynasty. He went to Yizhou to escape the war. At that time, Guanghai gathered a group of old, weak, sick and disabled during the war, and decided to call up soldiers instead of the monarch. He wanted to resist the aggression. Said that he would lead his subordinates to charge into battle, so as to protect the safety of Guanghai Navy.

However, when Tu Yu led his men to break through, they were suddenly attacked by assassins The attack, and many people wanted to capture Lord Gwanghae in order to ask for credit. Facing the ambush of the Japanese army, Dai Lijun and the royal family began to be suspicious of each other. None of them knew who brought the Japanese army in, and they didn't know what the other party wanted to do. For their own survival, these people began to intrigue.