For a very long time, the Baek family has been haunted by the legendary existence known as "Illishine." Hong Soorim, who has been imprisoned for ten years due to suspicions about this existence, finally shows a mark on his body upon turning twenty. The company that has been keeping him decides to strike a deal with both Chairman Baek and his son, Baek Wookyung. Wookyung offers a higher price than his father to meet Soorim. As Soorim accepts his fate, he tries to use Wookyung to his advantage. Despite their age difference, Wookyung finds himself drawn to Soorim...