A lawyer who’s ostensibly in good shape, Michael Clayton still has flab sagging and dangling from his body — years worth of weighty mistakes and fatigue at “fixing” problem-client concerns.

Clayton’s a legal sin eater, taking into his soul the culpability of those whose transgressions he cleans. What does he have to show for it? In a world of trophy wives and glamour homes, Clayton’s assets are gaseous, a marriage, equity and family pride all vaporized. Even his Mercedes is a loaner car from a firm that enables his self-destructive vices more than it employs his considerable talents.

These are just basics about Michael Clayton, which proves after only a half-hour to be a career-best role for George Clooney — even better than his Oscar-winning part in Syriana. In the next fiercely focused 90 minutes, Clooney elevates his game to give one of the most memorably realized portrayals of occupational anguish, frustration and salvation in this, or any, decade. (In particular, a scene in which Clayton addresses his young son’s potential becomes a transcendent confession.)

Clooney wastes nothing, and the film is just as breathtakingly efficient. For his directorial debut, screenwriter Tony Gilroy (the Bourne films) uses even closing credits as part of a series of brilliant, knockout scenes. Don’t miss those credits, as they provide the movie’s only, and profoundly affecting, exhalation.

With cinematographer Robert Elswit, Gilroy’s direction often combines earthbound beauty with small messages of corporate revulsion in the same shot; one character’s death is both horrifically clinical and strangely poetic. His screenwriting specifics and surprises unfold with methodical care; he’s smart enough to know the power of a great jump scare and that attentive adult audiences will savor all the small, but circular, details in one of the smartest, classiest legal thrillers ever made.

Though Clayton’s official specialty at Kenner, Bach and Ledeen is listed as “wills and trusts,” his niche is making sure auto accidents, public drunkenness and other dirty blemishes disappear for clients. Crippling gambling debts long ago sidelined him from trial work, and Clayton now watches his peers reap big-billable benefits from corporate class-action suits farmed out to the firm.

It’s six years into defending U/North, an agricultural chemical company, in a class-action lawsuit alleging that U/North knowingly sold a weed killer that caused cancer. When the defense’s architect, lawyer Arthur Edens (Tom Wilkinson) storms into a Milwaukee deposition room, strips naked and spouts a stream of impenetrable gibberish, Clayton is called to spin and smooth over.

Namely, Clayton must placate U/North’s chief litigator Karen Crowder (Tilda Swinton), herself struggling to find her way in a foreign world of rich, old white men. Elswit’s claustrophobic camera makes perfect use of Swinton’s bony, porcelain face, a veneer that could crack at any moment.

After a smoking-gun memo surfaces to implicate U/North’s guilt, Clayton and the mentally unstable Edens become swamped in a crisis of conscience and, eventually, a deadly conspiracy.

Wilkinson has the Peter Finch-esque role from Network, as Edens is prone to similarly grand filibusters as intermittently funny as they are unsettling. While it seems that little can be done with a man who’s mad as hell and not going to take any more, Wilkinson gives Edens a soft, sad sense of self-alienation. His stream-of-consciousness screeds take the tone of an off-key Song of Myself.

One of Edens’ off-his-meds diatribes is the first bit of sumptuous dialogue heard in Michael Clayton, and the film bears out to be as ravishingly alive and crazily inspired as his words. Suspense never hinges on whether U/North is guilty — that much is obvious — but whether Michael Clayton will make it out alive from the battle between his temptations and redemption. Clooney makes the man a picture of imperfections in a perfect picture that’s one of this year’s elite offerings.