The story is set in Republican Shanghai. Four young people with completely different experiences in life come together to break into the underground world of “Qianmen Jianghu” and solve mysterious cases. Su Zi Quan (Ning Huan Yu) is quick-witted and calls himself the “number one master sleuth on earth”. Despite his excellent memory, he can’t recall his early childhood. His biggest weakness, however, is that he’s allergic to women. Whenever he comes into physical contact with a woman, he has to sneeze. Tang Dai Yun (Shirley Jin) is a pure and kind-hearted, but also willful rich young lady. While looking for her lost older brother, she meets Zi Quan. Joining these two is the cold butler of the Tang household Chen Yi Ming (Li Dai Kun) who has great fighting skills and is only gentle to Dai Yun, and Zi Quan’s childhood friend Lu Zi Xiao (Zhu Ya), the only woman he’s not allergic to.

相传“千门”由伏羲氏创立，在历史中不断演化发展，形成各门各派，涵盖赌术、骗局、易容术、催眠术、中国戏法等等，民国时期最为鼎盛。“千门”技艺概不外传，直到门中一少年为报杀父之仇，开始揭秘各中因果，世人才恍然大悟。 　　故事发生在民国时期一个“三不管”的地界，这里三教九流汇集，俨然是一个暗潮汹涌的小江湖。因一场离奇的案件，三个身份各异的年轻人走到一起，开始“组团”破案的历程。此后一桩桩超自然离奇案件接踵而至，各色光怪陆离的江湖奇人悉数登场，隐藏在所有案件背后的神秘力量慢慢浮出水面。