It is a warm and sad, desperate but strong story; it is also a story that is close to life and breathes with us. The story of "Deer King": When a group of flying deer is attacked, only one deer will jump out to sacrifice itself and save the lives of its companions-because it is born like this. The meaning of the birth of some lives is to live for death. After the death of his wife and children, Van En joined the death squad "Unicorn" in order to reunite with his family in another world with a legitimate reason, but he survived a battle in which the whole army was annihilated and became a slave imprisoned in the underground salt mine. One night, a group of mysterious black dogs attacked the salt mine, and everyone died, but only he who was determined to die passed by death again. After escaping from the mine, he found the surviving baby girl Yuna who was hidden by her mother, and the two have depended on each other since then. However, how can a person who has long abandoned himself and has no attachment to the world protect a newborn life? Hesar, a genius doctor, is called "the son of the devil" because the knowledge he is devoted to is not accepted by the mainstream. But he always believes that as long as he does not give up, he can find a cure for even the most difficult diseases. Hesar was ordered to investigate the salt mine incident and learned that the escaped slaves might hold the key to solve the mystery, but he did not know that he would uncover a horrifying conspiracy... When the fate of the two people accidentally intertwined, a shocking story unfolded.