One day, Do Kyung-soo's favorite brother Moon Hao-cheon died unexpectedly, and he vowed revenge. After a year of preparation, he entered his brother's former organization to investigate the truth. Bian Baekhyun always believed that Moon Haotian's death was his fault. He knew Do Kyung-soo, and he knew Do Kyung-soo's purpose but did not reveal it. Do Kyung-soo fell in love with Baek-hyun during the struggle, and Baek-hyun made up for what he considered his sins, waiting for Do Kyung-soo's personal execution.