et in the decadent 1920s, Temptress Moon tells the very complicated story of a wealthy family living on the outskirts of Shanghai. Their youngest daughter, Ruyi, is brought up as a servant to her opium-addicted father and brother. Meanwhile, her brother-in-law Zhongliang has a successful, if illegal, career seducing and blackmailing married women in the city. When he comes to Ruyi's home the two fall in love, and trouble ensues.

Overview from themoviedb.org