It’s every man for himself in the final season of “The Sopranos.” The New Jersey crew of captains, thugs, and murderers, led by its charismatic general, no longer manages its mid-range Mafia business with precision; the money doesn’t flow the way it used to, and neither does the blood. Loyalty has given way to doubt. The polluted air they breathe – from those hideous smokestacks and sickening stogies in the background of the show’s still-mesmerizing credit sequence – has poisoned them at last. The festering emotional wounds of previous seasons have opened up and bled profusely onto every frame. “You’re part of something bigger,” Tony Soprano (James Gandolfini) tells Paulie Walnuts (Tony Sirico) at the end of Episode 4, a reflective moment that reveals Tony’s latest and most powerful obsession yet: the fleeting magic of life itself.

The epic journey of Tony Soprano takes a surprising and heart-wrenching turn this season, in a manner that no critic who loves this show would ever want to ruin with disclosure. But it can be revealed, without stealing its impact, that the cumulative effect of this season’s first four episodes is to turn “The Sopranos” on its head, in ways impossible to anticipate. It will be difficult for “Sopranos” fans to view the results without flinching at the painful recognition of mortality on display in every scene, at every turn. The Tony Soprano that emerges from the shambles created by the calamitous events of the first four episodes borrows less from “Goodfellas” than “King Lear.” He is a tragic figure who has faced his demons at last, but too late to undo their damage.

Shake-ups in both of Tony’s families threaten to undo the delicate balance this season; it falls to Carmela Soprano (his long-suffering wife, played with spectacular dignity by Edie Falco) and Silvio Dante (his introspective lieutenant, given subtle new layers by Steven Van Zandt) to protect their precarious units from total collapse. After five seasons as Tony’s loser son, A.J. Soprano (Robert Iler, now with Von Helsig hair), at last listens to his mother’s pleading and steps up to responsibility; in fact, he oversteps this time around – but at least he has become more Michael Corleone than Fredo, and there’s the hint of an even bigger role for him in the family’s future. For Silvio, it’s a matter of keeping his mutinous captains from abandoning or even destroying the sinking Soprano ship – a task made worse by his own weaknesses, shown for the first time.

For those who come to each new season of “The Sopranos” wondering who gets whacked, there will be satisfaction of a different dimension. Characters die gruesome, grisly deaths, but not as acts of vengeance; this time, creator David Chase and his team of writers and directors use mortality as a means to a larger point. Kneecaps get broken, heads get blown off, and there’s even a hanging – but all in service to the season’s questioning of purpose and responsibility by every major player. Silvio, Paulie, new Soprano brother-in-law Bobby Baccalieri (Steve Schirripa) and a slimmed-down Vito Spatafore (Ray Abruzzo) now squabble over money and turf like kids playing Monopoly – except that their futures rest on every roll of the dice.

The whacking continues, but now it’s out of desperation, not calculation. A wonderful, brief turn by Hal Holbrook as John Schwinn, a terminal cancer patient, allows him to tease Tony about mob violence; after the doctors deliver Schwinn’s death sentence, he looks his new Mafia friend in the eye and says with a twinkle, “Maybe you could whack me?” After Tony winces, Schwinn acknowledges that he has gone too far. “Bad joke,” he says, even though it’s yet another example of the wicked, lowbrow humor that distinguishes “The Sopranos” from its big-screen inspiration, “The Godfather.”

It should be noted that “Godfather” references are more clear this season; echoes of that epic – from the suicide of Frank Pentangeli to lines like “difficult, but not impossible” to describe a prospective murder plan – remind us that the mobster milieu of “The Sopranos” owes a permanent debt to that classic trilogy. And the wit of “The Sopranos” sometimes reaches for a level of sophistication that makes the jokes implausible. When a cell-phone ring alerts family henchman Gene Pontecorvo (Robert Funaro) that he’s being beckoned by a boss, Gene’s wife archly refers to the call as “his master’s voice,” implying a summons from Tony. It’s a sly reference to the old RCA Victor logo that seems arcane and unlikely for a 21st-century character. Similarly, when Christopher Moltisanti (Michael Imperioli) comes upon an FBI agent in the neighborhood sub shop and sneers, “Oh, Sheriff of Nottingham, my kingdom for a mortadell’,” it’s a funny double reference, but not exactly realistic.

But these represent small weaknesses.This season’s “Sopranos” (20 episodes in all, to be delivered in two installments before winding up next winter) moves quickly to remind us why we didn’t mind waiting almost two years for its return. The writing continues to be impeccable and insightful; on “The Sopranos,” even throwaway dialogue from incidental characters could carry the show.”Truth be told,”Tony tosses out in a brilliantly understated metaphor while discussing the hauling business,”there’s enough garbage for everybody.”And as always, great performances abound from its company of regulars. Even in just a few brief scenes, Lorraine Bracco as Dr. Melfi manages to introduce a murky ethical question into the mix. Mr. Sirico as the dependably comical Paulie delivers a deeper and more morally complex performance than ever before. And among the show’s many great guest stars, Ron Leibman makes an especially memorable return to playing devilish characters – this one wearing a white lab coat.

It’s hard to describe the nuances of Mr. Gandolfini’s performance as Tony Soprano without revealing the surprises in store – but his achievements this season more than justify the financial steps HBO took to keep him after his threatened walkout in the winter of 2003. The same holds true for Mr. Chase, who wrote this season’s second episode – even among these four amazing hours, in a class by itself. He clearly knows where he’s going, and where he wants to end.That long-range vision separates “The Sopranos” from even a terrific series like ABC’s Emmy Award-winning “Lost,” where you get the feeling its writers wing it from week to week. This season’s first four episodes represent a perfectly realized story arc that completes one journey for Tony Soprano and begins another.

To call this series the best show on television diminishes its value. “The Sopranos” has achieved a level of artistic achievement that puts the experience of watching these episodes on a list of rare pleasures in life – the kind that might have come from hearing a new Beethoven symphony as he conducted it, or watching the paint dry on a fresh Picasso. No one will watch the show’s final season without weeping for Tony Soprano, or mourning his imminent departure from our midst.

dblum@nysun.com