In the internet age, a woman’s ability to fit a 12-inch cock down her throat almost seems humdrum. In 1972, it was a big deal. That’s when infamous skin-flick Deep Throat hit cinemas, bringing in $100 million and making a star of Linda Lovelace.

Though she was America’s most famous good-time girl for a while, Linda later became a born-again Christian. In her best-selling biography, she claimed she’d been forced to appear in porn by her abusive husband, Chuck Traynor. In the 1980s, she told the the Attorney General’s Commission on Pornography, “every time someone watches that movie, they’re watching me being raped”.

Lovelace adapts Linda’s book, taking a Rashomon-style approach to show us the success story as it appeared, before jumping back to reveal the hidden unhappiness. But whereas Linda (here played by Amanda Seyfried with winning vulnerability) condemned the porn industry, the film holds back. Perhaps for brevity, perhaps for taste – perhaps realising a single person’s story shouldn’t be taken as the closing statement on so complex an argument as the nature of pornography.

Amanda Seyfried and Peter Sarsgaard portray Linda and Chuck as a pair of indy lovers. She’s at first thrilled by the changes he helps her achieve – giving up smoking, losing her Catholic inhibitions and learning to enjoy sex – but things turn sour. Sex, we learn, can be a weapon, and love can be a form of control.

But Lovelace isn’t simply an attack on the liberalism of the Free Love movement. Linda’s conservative parents (played by Sharon Stone and Robert Patrick) champion marriage above happiness, rob their daughter of her own child and send her back to her abusive husband for the sake of appearances.

In one of the most touching scenes, Patrick asks his daughter if she became a porn star because of something they did. Though Linda cannot say it, the answer is, of course, “Yes”; they loaded her with guilt, and raised her to think of cruelty and submission as facets of love.

The pornographers come out of things comparatively well. Adam Brody as Linda’s Deep Throat co-star, Hank Azaria as the film’s director and Bobby Cannaale as the financier play their parts for laughs. Their claims that Deep Throat achieved mainstream success because of its artistry are self-evidently ridiculous and hardly worth the scandal: pop culture gave people the chance to see some tit and they took it. Like Fifty Shades of Grey or Keith Chegwin’s Naked Jungle.

Lovelace isn’t about porn – though, don’t worry lads, there’s plenty of that. It’s not even about sex. It’s about misogyny and power relationships. It’s a considered argument delivered by a strong cast. She may be held up by some as a victim of licentiousness, but the true story of Linda Lovelace is one conservative America might find hard to swallow.