In the Northern Song dynasty, a young man named Gu Ping An came to Qiantang to investigate an unsolved case left by his father, which is where he meets Song Shi Rui,a young woman worried about paying the "singles tax". In order to not pay the tax and also allow him to investigate the happenings of the people in Qiantang, they decide to team up and pretend to be a couple and open a restaurant together.