Perpetual Motion.

Niuniu, a wealthy middle aged woman living in Beijing, discovers that her husband is having an affair after coming upon a romantic e-mail. She knows only that it is one of her close friends but not which one. Determined to discover the truth, she invites her friends Qinqin, a ditsy actress, Lala, a successful artist, and Madam Ye, a property developer over to her lavish siheyuan home. There the four women share stories of their sexual past over food and mahjong. Niuniu, however, still has her plan to execute...