This long-lost masterpiece of gay erotic cinema centers on a handsome young stud who rides his motorcycle through a myriad of sexual encounters, from a soccer game's locker room to a dreamy and unsettling orgy where the film reaches its melancholic peak. Newly scanned in 2K from the original camera negative and directed with absolute grace by the mysterious Dietrich de Velsa (aka Francis Savel / Frantz Salieri): this former painter was also the owner and artistic director of one of the first transvestites' cabaret of Paris, La Grande Eugène. Years later, he collaborated with Joseph Losey on Mr. Klein (1976) and Don Giovanni (1979). EQUATION TO AN UNKNOWN is his only film and stands without a doubt as a masterpiece and the best French gay adult film ever made.