Every time I see a new Kevin Spacey movie, I expect the world from him, and every time he delivers the galaxy.

Arguably the greatest actor currently working in motion pictures, he is capable of putting across leagues of depth with the subtlest, most insignificant glance. He can play menacing or meek, ardent or indifferent, nervous or non-nonchalant with equal dexterity.

Look at "Midnight in the Garden of Good and Evil," "The Negotiator," "L.A. Confidential," "The Usual Suspects" or any of his recent roles and just try to imagine another actor in the part. It simply can't be done. Spacey doesn't act, he embodies his characters viscerally from the inside out.

In the astounding "American Beauty," this eminent actor gives a precisely -- yet almost subconsciously -- unbalanced performance as a shell of a generic American father thrust suddenly into an extreme mid-life crisis by rampaging fantasies about his teenage daughter's coquettish best friend.

Haunted by suburban ennui, his perceived success with this girl (an attention-starved lass who teases him for kicks) leads to delusions of rekindled sexual prowess and a shift toward self-centered, devil-may-care liberation (he quits his job, blackmails his boss and buys a GTO) that upsets the already his inharmonious and disjointed household.

The way Spacey inhabits this pathetic soul is remarkable, carrying stress in his pinched shoulders and making him seem like a textbook example the worst the male sex has to offer, yet garnering sympathy and even empathy from the audience.

But Spacey is only one member of an extraordinary cast that adroitly walks a high wire between this story's wry irony and its dark drama, as his character's shift in lifestyle effects those around him and leads to misunderstandings, emotional fallout and the most extreme of unimagined consequences.

Thora Birch (Harrison Ford's little girl in "Patriot Games" and "Clear and Present Danger") plays his insecure and disaffected teenage daughter, who can't bear her father's rampant lusting after her friends and retreats into a strange romance with an abused and off-kilter neighbor boy (Wes Bentley, "Beloved") that videotapes her through her bedroom window, when he isn't being beaten by his volatile, retired Marine pop (Chris Cooper, "October Sky").

Annette Bening more than holds her own as his seriously wound-up, glass-half-empty wife who is determined to maintain a Norman Rockwell facade no matter what misery she inflicts on herself and her family.

As the conceited young siren whose entire self-image revolves around her sexuality, Mena Suvari ("American Pie") mines her role for deeply buried abandonment issues and other masked emotional baggage that might lead her to crave the affections of a man more than twice her age.

The first motion picture directed by theater veteran Sam Mendes ("The Blue Room," the "Cabaret" revival), "American Beauty" was written by Alan Ball, another Broadway vet and feature film rookie. Yet even with these relative greenhorns holding the reins, it is easily the most accomplished and original American film released so far this year.

Just the way Mendes and his stars create a camaraderie between the audience and even his most contemptible characters is so effective it's near genius. But his total understanding of the impact film can have comes across most clearly in a string of deliciously rendered fantasy sequences that probe our anti-hero's libido for images of a naked Suvari floating in a sea of rose petals. The image is absolutely indelible.

Almost lyrical in its balance of familial tension and pitch black observational farce, this film weaves a completely engrossing tale of the underbelly of middle-class Americana that has already caused the years first serious Oscar buzz -- which is 100 percent justified.

Even if the picture isn't nominated, Spacey should be. This is the best performance of his career (until his next one, no doubt), and for my money any Kevin Spacey tour de force -- which is what this is -- pretty much automatically trumps any other performance we might see between now and December 31.