For a sex addict, perhaps the most crippling loss is that of the joy of pursuit. For even the most lecherous skirt-chaser, there is a pleasure derived from the hunt, a way of finding one’s raison d’etre through cheap orgasms. Once even that provides no pleasure save for the temporary satisfaction of a compulsion, the addict is truly left with nothing. There is no intimacy, no pleasure, no thrill. There is only the next climax, though that term feels like a misnomer, as there’s nothing climactic about it. From here, there is only the inevitability that the fragile paradigm of satisfying that most primal of urges will collapse.

Shame is primarily about what happens when that collapse occurs, and the depths to which an addict will sink before allowing it to happen. Brandon (Michael Fassbender) is steely and handsome, able to facilitate sex whenever and wherever he pleases with next to no effort. One of the film’s many brutal ironies is that Brandon’s total lack of effort in meeting women makes him far more appealing. An early sequence, in which Brandon reduces a married woman on a subway train to a quivering, conflicted mess with no more than a long, passive gaze is brutally telling. The only genuine show of emotion on Brandon’s part comes when he is unable to find her in time, and loses out on his temporary reprieve.

As Brandon, Fassbender delivers what is definitively the best male performance in any film released this year. There are long passages in Shame without dialogue, a master touch on director Steve McQueen’s part; Fassbender is more than able to establish everything we could ever want to know about Brandon without a single word. This is a naked performance in every way, including the literal; much has been made of Shame’s NC-17 rating, and it keeps well with the MPAA’s general mission statement that sex is okay in films as long as there’s no actual pleasure involved. For all the graphic sexuality on display, Shame may be one of the least erotic sex films ever made. Late in the film, McQueen closes in on Fassbender’s face mid-orgasm, and there’s no pleasure, no catharsis. His face is a perverse mask of agony.

The few solid details about Brandon mostly come from his interactions with Sissy (Carey Mulligan, equally fearless), his estranged sister who forces her way back into his life. Their first scene together alone suggests that these two both lack familial intimacy and share a different kind that’s at once wholly inappropriate and deeply painful. Brandon wants Sissy gone, not just because of his sudden responsibility for another human being, but because she presents both a block to his way of life and a reminder that perhaps there’s something wrong with him. Like any addict, Brandon is surrounded by enablers, a city full of them (New York has never looked colder), and does not appreciate interference. Additional trouble comes in the form of a coworker who finds herself on a date with Brandon; her attempts (in vain) to chip away at Brandon’s meticulously crafted walls are heartbreaking.

Shame slowly crescendos to a nightmarish sequence of hedonistic excess, in which Brandon goes on a night-long journey into the seediest, most perverse parts of the nighttime underworld. It’s a troubling sequence on multiple levels (it’s hard not to cringe a bit at his bottoming out partially involving a trip to a bathhouse), but it’s impossible to look away from Fassbender, who attempts to forcibly exorcise his demons in one fell swoop, continually ignoring the nagging anchor of his sister’s voicemails begging him to come home. In Shame‘s purview, there is no homecoming for Brandon. There is only the hunt, and the hope that at least this will give him a modicum of pleasure someday.