Choi Kang-ta is a super agent with a feared reputation who gains powers similar to a god. As a child, he lost his parents and was adopted by an American couple. After becoming an adult, he returns to Korea to exact revenge on the murderer of his father. He learns that there were four people responsible for his father's death. In the midst of carrying out his plans, his partner Vivian betrays him, putting his life in danger. He is nursed back to health by Bo-bae, a reporter he met by chance, and as he falls in love with her, his beliefs are shaken. After recovering from his wounds, he settles down in a slum neighborhood where he befriends the poor residents. For the first time in his life, he is surrounded by warmth and love in his new home, and finds peace within himself. But Hwang Woo-hyun, a high-ranking official at the Korean Central Intelligence Agency and heir to the Hwanglim Group empire, becomes enraged with jealousy that Choi Kang-ta stole Bo-bae away from him and decides to have him eliminated.