Behind the Green Door (1972) review

Well-regarded classic porn actually dodges some of the problems with the genre - namely the difficulty linking the disparate scenarios together, the terrible acting and the poor dialogue - by making it virtually one very long, somewhat mysterious orgy that starts with "all American girl" Marilyn Chambers being kidnapped and forced to participate in a live sex show. The virtual silence - aside from moaning and slurping - is actually quite effective, as is the minimal score (which doesn't entirely fall into the "porn music" cliché) - the grinding organs and anonymous sex provide all the thrills that were presumably safe in the early seventies. The orgasm sequence, done with silhouettes and slow motion, is curiously mesmerizing.