Something akin to American Psycho only with murder replaced by sex, Shame is the sophomore feature from British artist-turned-filmmaker Steve McQueen – no relation to the late movie star.

The suddenly ubiquitous Michael Fassbender stars as Brandon, a wealthy Manhattan corporate nobody who has a sex addiction. (Or so the film wants us to believe – for much of its running time, Brandon doesn't seem to be getting any more action than any other good-looking, successful single New Yorker might.) When his younger sibling Sissy (Carey Mulligan) suddenly shows up needing a place to stay, Brandon becomes even more morose than usual, even as his fixation on pornography, hookers, and one night stands continues unabated.

That's pretty much it, in terms of story.

There's so much potential in making a film about sex addiction. Although the jury's still out on whether it's a genuine problem like alcoholism or drug abuse, it's still compelling subject matter. But it remains maddeningly unclear what McQueen is trying to say with this film. He and cowriter Abi Morgan come across, frankly, as scolds – the film's very title suggests a Victorian tut-tutting of Brandon's promiscuous lifestyle, even though it doesn't really affect his work, always involves consenting adults, and isn't particularly deviant.

Instead of suggesting that our society's emphasis on being "sexy" is creating people like Brandon who are unable to sustain healthy romantic relationships, or even saying that Brandon's soulless obsession with intercourse is a dark path that any single, lonely person might take, the story infers – fleetingly – that Brandon's problem (and Sissy's too – for although she's not a sex addict, she's still a mess) stems from, yawn, some kind of abusive upbringing.

Despite this handful of hints, nothing is ever confirmed in what I assume is an intentional avoidance of pinpointing a cause for Brandon's problems. In one sense, McQueen has a point – after all, in films about drug addiction, we're not usually shown how or why the character first started using drugs. There's no need, since we can easily guess. The real point is how the character deals with the consequences. But since Shame keeps us at such a distance, rendering its characters as ciphers, it left me unmoved. I wish McQueen, Fassbender, et al could have shed a bit more light on their subject.

I'm still glad I saw Shame, only because it's made me think a lot about what I would have done to make it a better film. And for a writer/director, that's a weirdly enjoyable experience. The rest of you can take my word that Shame can be skipped, notwithstanding strong performances (albeit with slippery American accents; with a British cast and director, why didn't they just set the story in London instead of New York?) and a lush string score by relatively unknown composer Harry Escott.