WWW- Produced in 1978, Debbie Does Dallas, www.xxxdeepthroat.com is one of the five top-grossing porn films of all time. Most people who remember it regard it with some affection, either for its relatively innocent ’70s flavour, or for its cheesy parody of the real Dallas Cowboys cheerleaders.

What few know is that there is a darker side to the story, from the lawsuit filed by the Dallas Cowboys over the use of their name, to the death of Mafia boss Michael Zaffarano, who had bankrolled the film, and the disappearance of the film’s star, Bambi Woods. The search for Woods and her co-stars drives the narrative of this documentary.

Two of the film’s male stars, Herschel Cohen (stage name Herschel Savage) and Rob Everett (Eric Edwards), discuss it candidly, though it is perhaps telling that only the film’s male stars still work in this famously toll-taking business. Most of its female stars, the narrator says, declined to be interviewed. One, he adds, emailed to say she wanted nothing to do with a business that had given her nothing but exploitation.

Pornography, and in particular America’s San Fernando Valley porn business, is a fascinating story, culturally, socially and financially. In the end, the documentary can’t resist the lure and it becomes a little less about Debbie Does Dallas and more about the porn business as a whole. It’s nicely done, intelligent and respectful, but it is somewhat explicit. You’ve been warned.