Determined to become No. 1, Su Xianling is a rookie assassin from the Sifang Society, a renowned assassin organization. After she failed to rescue her fellow disciples, she takes over their unfinished assignment. Her task is to assassinate Dongfang Jing, Lord of Luoyi City. However, Dongfang Jing, who appears to be a fatuous ruler, turns out to be the employer behind this task. He's a man of distinguished bravery and ingenuity and is using Su Xianling's identity as a decoy. They collaborate in both light and shade, being both enemies and partners. In this game of love and rivalry, they fall for each other gradually.