The caustic About Schmidt showcases Jack Nicholson’s greatest performance in decades.

It's funny how often actors can appear on screen without actually exercising their craft -- which is to say, acting. Jack Nicholson never stopped making movies, but it's been a long time since he did anything which could be called acting in any more than the most technical sense of the word. He didn't start off as a star, or even a star-in-waiting. While a certain alienated ferocity links his landmark '70s performances -- in Five Easy Pieces, The Last Detail, Chinatown and One Flew Over the Cuckoo's Nest, among others -- they were more than repetitions; they were sculptures cut from the same block, sharing material but distinct. By the decade's end, Stanley Kubrick, never particularly attentive to the nuances of performance, had helped Nicholson turn himself into a caricature, and for 20 years, he played variations on The Shining's theme as often as not. When he strayed from the formula, his non-"Jack" performances often seemed driven more by obligation than inspiration, as if he had the desire to break free of his onscreen persona, but not the will.

The reasons why Nicholson has chosen this moment to shake off the years of dust aren't important. All that matters is that he has. About Schmidt isn't just the best performance Nicholson has given in nearly two decades; it's practically the only one that matters. Nicholson doesn't so much discard his star image as aid director Alexander Payne in destroying it. It's easy for stars to play "brave" by dipping their manicured toes into the misery of "ordinary people," or by strapping on some showy deformity (as Nicholson himself did in As Good As It Gets). But it's far more honest to play outwardly unexceptional people as we all see ourselves: as the star of our very own show. From the outside, Nicholson's Warren Schmidt may seem like an average schmo, but seen through his eyes, he's King Lear.

When we first see Warren Schmidt, Nicholson's Nebraskan insurance salesman, he's sitting at his desk, slack-jawed, waiting in silence for the wall clock to tick off the last seconds of his career. At his retirement party that night, a colleague bestows the highest praise he can think of upon him: "You devoted your life to something meaningful -- to being productive." The best Schmidt's friends -- who, incidentally, we never see again -- can say of him is that he was an exceptionally enthusiastic drone.

Schmidt, who skips out on his own party to have a quiet drink at the bar, finds the days at home dragging on endlessly; he still wakes just before 7 a.m., but he's got nowhere to go. Spending more time at home with his wife (June Squibb) is apparently no comfort, so one night, Schmidt calls a number off the television to sponsor a young Tanzanian boy, and before long he's sending letters off to the other side of the world on a regular basis, pouring out his heart in a way you sense he never has. Payne is too cagey to allow the sentiment to pour out uninterrupted, but if you can listen past the laughter every time Nicholson starts a voiceover with the words "Dear Ndugu," the extent to which Schmidt has for years lacked an outlet for sentiments both trivial and profound becomes pitiably clear.

When even his meager domestic security is stripped away from him, Schmidt hits the road in the 35-foot Winnebago that's been clogging up his driveway, but as in Lost in America, to which About Schmidt might be a sort of acid-tongued cousin, he finds the American dream warped almost beyond recognition. Crossing the Midwest, he discovers his childhood home has been replaced by a tire store (as in Grosse Pointe Blank, "you can't go home again, but you can shop there"), while his only daughter (Hope Davis) desperately tries to prevent him showing up even a few days before her impending marriage to a water-bed salesman (a rat-tailed Dermot Mulroney). On those rare occasions when he encounters genuine kindness, as with an unsettlingly cheery trailer-park couple (Harry Groener and Connie Ray), Schmidt doesn't know how to handle it; the emotions filling him are so alien he has to flee the camper in a panic.

About Schmidt has been charged in some quarters with condescending to its characters, but that's only true if you think it's a sin to depict Midwesterners as anything other than hard-working, noble people of the earth. Payne, a native Omahan who's made all three of his features in the town he only recently abandoned (Citizen Ruth and Election are the others), has the ambivalent feelings anyone has toward the place he grew up, but his inclination toward satire rarely shades into misanthropy. (The scenes at Schmidt's future in-laws' house are the exception, with Kathy Bates as the libidinous matriarch of a freak-show household.) Payne has an eye for what's usually considered ugliness, which extends to his star: Nicholson, a year younger than the 66-year-old Schmidt in real life, is filmed with no visible makeup, and the camera taking in the hair in his ears and nose, even his sexagenarian ass. (George Clooney need not dismay.)

The Midwest serves Payne as a satirist not because the hills are brimming with Candides ripe for a rude awakening, but because it's so easy to play off coastal assumptions of heartland virtue. But while Citizen Ruth's spray-can huffing unwed mother or Election's back-stabbing high school politician at least made a showing of aw-shucks affability, Schmidt has lost any reason to put on a good face, and any conviction that it would help matters. "I am weak, and I'm a failure," he despairs when things seem their worst. "There's just no getting around it." Payne's not cruel enough to leave Schmidt in the lurch for good, but his salvation is arbitrary enough to seem quite conspicuously like a gift from the gods. It's a gesture of faith, but also one that reminds us how tenuous faith can be, and how sometimes unwarranted.

About Schmidt, Directed by Alexander Payne, a New Line release, Opens Friday at Ritz East