Ever wonder what — and who — really goes down in the imposing brick fortress at Mission and 14th, here in San Francisco? This adults-only doc (produced by James Franco and screened at Sundance this year) goes behind closed doors at the Armory to reveal purveyors of fetish porn, working and wanking on the edge of big-business BDSM.

Kink.com founder and CEO Peter Acworth is an erudite Englishman whose lowdown videos and websites are adored by hardcore players with a penchant for inescapable bondage, shagging machines, and no-holds-barred debauchery. A savvy impresario of sub/dom power exchange, Acworth has built an empire on the whipped backs of fearless performers and the outré visions of creative adult filmmakers who enact seriously sexy scenarios throughout the Armory’s medieval arenas.

The film contains many take-it-till-it-hurts moments, as Maitresse Madeline, Van Darkholme, and their fellow kinksters discuss turn-ons, assert sex-positive feminism, stress safety during shoots, and refute charges of violence in their admittedly extreme modes of sexual expression. Provocative, surprisingly poignant, and just a tad painful (in a good way!), kink is a titillating treat for adventurous viewers whose tastes are far from vanilla.