First things first. If you want your porn to have a happy ending, Gia is not for you. If you want it to tell no more story than can fit on a pinhead; if you think character and personality are decoded by how many cocks a girl can take at once; and if you want to get down to all those nasty things that your own partner won’t let you try... you guessed it. Gia is not for you.

If, on the the hand, you watched and maybe wept through Angelina Jolie’s performance as Gia Marie Carangi... yeah, a porno version of that struck me as a fairly gruesome prospect too, so rest assured, the name really is the only similarity. Well, that and the story arc, following a beautiful young model (Sunny Leone) from her so tentative introduction to the worlds first of glamor modeling, through topless and nude, into porn, onto stardom - and then the classic Hollywood ABC: addiction, burn out, collapse and death. None of which is portrayed with anything less than sensitivity, drama and, dare I say it, class?

Like the original Gia (and the Rutles movie, for that matter) the set-up here cuts between scenes from the titular heroine’s life, and interview clips with people who knew her - Herschel Savage, Randy West, Ron Jeremy and Debi Diamond are among the familiar faces who play themselves, reminiscing on their own experiences with Gia. It’s a clever trick, convincing the viewer that this is a true story; that the lovely Gia actually existed; and that her story really did end this tragically.

But they are not the movie’s own ace cards. Simply in terms of meeting every demand the movie makes of her, Leone is phenomenal. From starry-eyed ingenue to stoned-out addict, from a human wreck suffering the agonies of withdrawal in rehab, to a shadow-woman facing up to her imminent death from a hospital bed, she does not put a foot wrong, and while her sex scenes are all memorable, the most impressive comes following her break-up with boyfriend Dirrty (Ariel King) - when she is called upon to fuck him one more time for a movie. Her disgust and disdain may not be porn movie conventions, but they are convincing.

Indeed, King plays his role magnificently throughout and elsewhere, Lexi Belle (as one of Gia’s porn star contemporaries) is addictively dizzy and giggly. And then there is Tori Black, who turns in a performance (as Gia’s live-in lover, and to-death partner) that you simply cannot tear your eyes away from, and that is long before we consider the two sex scenes she shares with Leone. But I will say, the pair turn in what is probably the hottest girl-on-girl-on-chainlink fence sex scene you will ever see. Ever.

So, an adult movie that values plot, story and dialogue as highly as it prizes the sex, and which pulls them both off extraordinarily well... but not, for all of its qualities, a movie that will sit easily on the average viewer’s pile. Asking some very uncomfortable questions about certain aspects of the adult industry, and allowing that industry’s own stars to illustrate them from personal experience, raises Gia far above the traditional fuck, suck and pop shot fare that we have grown to expect.

Likewise, the knowledge that we are on a rollercoaster ride to tragedy ensures that even the most steaming sex scenes are undercut with a sense of foreboding - most notably when Gia settles down to “direct” some movies of her own, and is so wasted she can barely even focus. Lexi Belle and Dale DeBone put on a wonderful show, but Gia’s dead eyes and MIA persona haunt the camera regardless. By the time Jennifer Dark and Ryan Driller are ready for their scene, the viewer could be excused for fast-forwarding through it, simply to reach the next phase of Gia’s disintegration.

Released in 2010, Gia was promoted with the claim that it was “the most controversial [adult] movie of the year,” and maybe it was. But I prefer to think of it as one of the most affecting, and effective, and one that exists on a cinematic plateau that has few directors and actors have even dreamed of visiting ... let alone succeeded in attaining.

If you only buy one XXX movie this year, make it Gia. But don’t expect to be in the mood for fucking once it’s over.