Cheng Yu, the lonely sojourner in the bustling city, goes in and out of a different empty house every day, prying into the city's secrets. He doesn't know why he's here, nor does he know where he'll go tomorrow. By chance, he saw the eighteenth-string actress Hu Mengya in an online drama, but never imagined that in the next seventeen days he would experience the three most important points in his life.

In an attempt to investigate the origin of the "bloody handprint", Peng Yutian, the most unreliable detective of the Sixth Department, travels to Luoyang. To preserve his agency's reputation, Peng is forced to use in the Qingyun Paviliona variety of tricks that aren't always fair.