In the opening credits of Darren Aronofsky's The Wrestler the camera pans along dozens of promotional flyers of wrestler Randy "The Ram" Robinson (Mickey Rourke). The repeated images disturb because they make it clear how damaged Mickey Rourke's face is. Audiences expecting to see the handsome, insolent features they recall from Coppola's Rumble Fish (1983), Alan Parker's Angel Heart (1987) or Adrian Lyne's Nine 1/2 Weeks (1986) will be shocked to see the actor's altered appearance.

It's not that Rourke looks older, but rather the once-fine lines of his face now appear in Aronofsky's unsparing close-ups to be distorted, tightened and strangely puffy, apparently on account of boxing injuries combined with plastic surgery. As a result, it's impossible to take your eyes off that face and in any case this performance is a landmark, a torrent of agony and energy and personal vindication for an actor who appeared all but washed up. No wonder the cineaste David Thomson once said of Rourke: "He could come again." Aronofsky succeeds in eliciting work of sincerity from Rourke just as he did with Ellen Burstyn in Requiem for a Dream (2000).

Each of the characters in this picture has been brutalised by circumstances. We find Randy inhabiting a trailer park somewhere in snow-covered, urban New Jersey. Aronofsky allows a shaky hand-held camera to linger over the details of social decay familiar from Requiem for a Dream.

Twenty years after his heyday as a professional wrestler, Randy is reduced to performing in local dives on the weekends while packing boxes in a supermarket during the week. The wrestlers plot their moves in a civilised and jokey way before entering the ring. As Randy tells an opponent: "A bang of the ropes, superkick, Ram-jam. Then we go and have a beer." Soon, however, the desperate need for money - his landlord has locked him out of his trailer - forces Randy to fight in a debased form of the sport. In this extreme wrestling any tactic goes and participants deploy weapons such as barbed wire and staple guns. I should warn you, these scenes slap the viewer around the head with their documentary-style violence; several times, the critic sitting next to me held her hands in front of her face.

The batterings and mutilations that the wrestlers inflict on one another speak of a deep-seated self-disgust and inner emptiness among people who hurt themselves for money. And Aronofsky presents no facile prospect of redemption. Randy's love interest, "Cassidy" (Marisa Tomei, pitch-perfect), dances and takes off her clothes at Cheeks lap-dancing club to support her and a nine-year-old son. She has dark rings under her eyes and is past her best. Her real name is Pam, she confides in Randy, once he becomes more than a customer.

A crisis comes when, after an extreme wrestling bout, Randy collapses on the floor of the dressing room. He wakes up after heart bypass surgery to be told he must never wrestle (or shoot himself full of body-building steroids) again. He cancels the forthcoming comeback fight, a reunion after 20 years with a great opponent called The Ayatollah, and concentrates on forming a relationship with Pam (with limited success) and rebuilding one with his estranged daughter, Stephanie (Evan Rachel Wood).

But Randy's selfishness confounds any hopes of lasting trust and intimacy in either case, although Pam is attracted to the aura of martyrdom that surrounds Randy and even quotes from The Passion of The Christ.

In the case of Stephanie, who hates her father to begin with for the years of missed birthdays, he brings her round with presents and an appearance of concern. They arrange to spend Saturday evening together but instead he drinks too much and forgets all about it. In truth, Randy cannot connect with other people except in the ring. The ring is the only place, he says, that he feels real, deafened by the screaming of his fans who, by the way, look like a young, flabby and pasty-faced bunch of inadequates.

Randy takes a job at the supermarket deli counter under a petty authoritarian supervisor but cannot stand the daily humiliation of serving up half-pounds of (you guessed it) boloney and potato salad to New Jersey homemakers. In a scene that provoked horrified gasps in the theatre, Randy quits his job with his characteristic flair for drama, by deliberately injuring himself on a meat slicer.

The climactic reel sees Pam, after having told Randy to buzz off, returning to rescue a hero she sees in a rather warped way as Christ-like. She finds him psyching himself up for the big contest with The Ayatollah. There is a dismal inevitability about the final scenes as he resists her entreaties - "what about your heart?" - and explains that here in the ring is where he belongs, that no one loves him out on the real world. During the final wrestling bout we see Randy clutching his chest in pain.

The Wrestler is not a family picture. It deals with the lives of people at the edges, people who have fragmented lives with no solid families and who lack the reassurance and bolstering that permanent close ties and an inner life provide. Its violence is disturbing. But also, for all that, it feels thrilling and uplifting to witness something great and true in Mickey Rourke's performance. He has come again.