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

　　故事发生在里昂。玛丽（阿诺克·格林布戈 Anouk Grinberg 饰）是一个妓女，和其她由于生活所迫而从事这份尴尬的职业的女人们不同，玛丽是打心底里热爱自己的工作的，无论她的客人是何等的丑陋和年迈，她都能以十二分的用心和温柔将他们服侍的心满意足。一次偶然中，玛丽在自己的家门口结识了昏睡在那里的流浪汉弗朗西斯（奥利维·马丁内兹 Olivier Martinez 饰），善良的玛丽不仅将弗朗西斯带进了家门，更用美味的食物和自己的身体温暖了这个可怜人冰冷的心灵。
　　玛丽和弗朗西斯恋爱了，她甘愿用自己的身体换取金钱，来满足无所事事的弗朗西斯提出的种种要求。好景不长，弗朗西斯个性中的缺点逐渐显露，他不仅对玛丽热爱的职业表现出了反感，更和一个美甲女郎产生了暧昧的关系。很快，弗兰西斯便因为触犯了法律而锒铛入狱，与此同时，玛丽也站在了人生的十字路口之前。

　　一位中年警察，乔治.德布拉什，努力帮助和保护马诺尼，他已经知道，因为他们都还年轻。他命令他的年轻同事和朋友，监视迪迪埃·塞隆，和马诺尼的妻子和其儿子。与此同时，他开始与迪迪埃·塞隆的妻子芭芭拉开始交往。

　　故事设定在中国香港，艾曼纽（诺米·梅兰特 Noémie Merlant 饰）去当地出差，因此展开了一趟与许多人相遇、寻找失落的欲望的旅程，她遇上一个叫Kei的男子，对方却一直躲避她。

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