戴和住在隔壁的姐姐有血缘关系，从小就对他照顾有加。当结婚后去了东京的姐姐回来时，他被遗忘的欲望开始萌芽，两人在父亲不知情的情况下完全沉迷于性爱
丹尼尔（吴毅将 饰）是衔着金汤匙出生的千金大少爷，受过高等教育，平日里作风温文尔雅谦和有礼，但背地里，他却是一个残暴而又疯狂的色魔，专门喜欢对手无寸铁的妇女施暴。一直以来，丹尼尔都非常喜欢住在隔壁的名为小娴（关秀媚 饰）的姑娘，然而小娴已经有了男友亚辉（张家辉 饰），因此她和丹尼尔之间是绝对没有可能的。 小娴常常唤来好友冰冰、劳拉和娜塔莎三人到家中小住，一天，当四人又一次齐聚一堂时，丹尼尔趁着月黑风高潜入小娴房中，奸杀了冰冰。亚辉和他的搭档宝文（朱茵 饰）做梦也想不到，这一切的真凶竟然就生活在他们的身边。
This long-lost masterpiece of hardcore gay erotic cinema centers on a handsome young stud who rides his motorcycle through myriad sexual encounters, from a soccer game’s locker room to a phantasmagoric and deeply melancholy orgy. A labyrinth of all-male fantasies whose outstanding beauties always end up fading away while leaving their sensual protagonist dealing with his own loneliness, EQUATION was directed with supreme grace by the mysterious Dietrich de Velsa (aka Francis Savel/Frantz Salieri). A former painter, de Velsa was also the owner and artistic director of La Grande Eugène, one of the first drag cabarets in Paris. Years later, he collaborated with Joseph Losey on MR. KLEIN (1976) and DON GIOVANNI (1979). His one and only film, EQUATION TO AN UNKNOWN stands as one of the most extraordinary erotic films of all time. “The most melancholic porn film I’ve ever seen. It’s very sad, and aesthetically beautiful. Just a young man wandering through several depictions of love and choreographies of love-making; it’s like a ceremony, a ceremony of fantasies, especially the last sequence where the main character recalls all his previous fantasies, which come one by one around his bed and make love to him. I think it’s one of the most beautiful film sequences of French cinema.” –Yann Gonzalez
苗伟（江国斌饰）替继父顶罪入狱，在牢房内受尽屈辱，每夜只有幻想与自己从小青梅竹马的恋人温妮（徐若瑄饰）亲热来慰藉痛苦。苗伟出狱后，靠打散工为生，去找温妮重叙旧好，却发现她已有了未婚夫乔治。一日在party上温妮见乔治谈兴正浓，于是就叫苗伟先送自己回家。二人开车在山上玩耍，回家后却见愤怒的乔治兴师问罪，认定二人有私情。温妮与乔治争执后分手，遂与苗伟结婚。婚后二人很幸福，然而苗伟却因为狱中过多的屈辱与性幻想而导致现实中无法与温妮正常接触，二人开始出现隔阂。心烦意乱的苗伟于是去找旧情人玲姐满足生理需要，而这个秘密在一个雨夜被温妮偷偷查到......
