'SIX FEET UNDER' WAY ABOVE MOST TV.

Byline: DAVID KRONKE TV Critic

NEAR THE END of ``Six Feet Under's'' debut season's finale, Nate (Peter Krause), the good-hearted but bewildered guy railroaded into working at the family-run funeral home, was asked by a distraught mourner that key question: Why do people have to die? Nate, pondering the question momentarily and reflecting on his own recently diagnosed life-threatening malady, answers, ``To make life important.''

Creator Alan Ball buried the lead: He waited until the 13th episode of his series to reveal the theme of his brilliant series. In ``Six Feet Under,'' it's all important - the messy minutiae of life, the details in even the most minor supporting character's personalities and, of course, the big questions: Why are we here? How do we fill our lives with meaning?

``Six Feet Under'' may be the ultimate HBO series. Sure, ``The Sopranos'' established unequivocally the pay-cable network as the destination for quality television, but even it deals, however ingeniously, with some fairly conventional dramatic tropes - the admirable anti-hero, sex and plenty of violence. The broadcast networks, however belatedly, are figuring out how to at least somewhat emulate its template (NBC, for example, has a pilot about a drug kingpin in the works).

Very little about Ball's series, on the other hand, would ever make it onto network television. First off, it's largely about grief and the dramatically diverse ways people cope with it; secondly, the characters are complex, drawn as much as possible from real life as from genre drama. It's hard to imagine any other television show (or, even, film) boasting a lead character yearning to reconcile his homosexuality with his deep spiritual convictions that include the religious edict that homosexuality is a sin.

``Six Feet Under'' is, for the most part, so exponentially richer than other TV shows, than most movies, that in these days of dumbed-down entertainment force-fed us by media conglomerates, it's practically a miracle.

Season two opens tonight with Nate, who has been diagnosed with a vexing brain malady that might - or might not - trigger a debilitating stroke at any second, coming to terms with his new-found mortality. His girlfriend, the vivaciously - and, sometimes, scarily - mercurial Brenda (Rachel Griffiths), seems to be withdrawing from him, forcing him to keep his condition from her.

Meanwhile, David (Michael C. Hall), who spent most of last season coming to terms with his homosexuality and emerging from the closet, will spend this season trying to rekindle romance with Keith (Matthew St. Patrick), the proudly gay policeman who is currently in another relationship, one that is tested when Keith discovers his dope-addled sister's heartbreaking negligence of her daughter.

Also, younger sister Claire (Lauren Ambrose) slowly but certainly discovers what a scumbag her current boyfriend (Eric Balfour) is, in what's probably the show's most sensationalistic subplot. And their mother Ruth (Frances Conroy) attempts to cope with her recent discovery that David is gay - she throws a dinner party that goes disastrously awry, thanks to a tab of ecstasy that was deposited in an aspirin bottle and is inadvertently ingested.

Ruth is probably the least well-drawn, most peripatetic character of the bunch - what can you say about a widower who comes on sexually to a surly florist in one episode, then gets mixed up with a clearly dubious self-help enclave in another?

Each episode features a ``death of the week'' - an untimely demise that gives Nate and David a paycheck and unveils a new group of mourners, who range from laughably fatuous to deeply moving. Frequently, the corpses themselves emerge to convey cryptic messages from beyond to the funeral home's employees.

``Six Feet Under'' demands, in its storylines, that people take responsibility for their lives, excoriating irresponsible parents and narcissistic selndulgence of all stripes. It also ruminates frequently on the afterlife - what, if anything, awaits us? It's a debate heartily pursued that you won't find elsewhere on TV unless ``Crossing Over's'' host is baiting a few more rubes.

SIX FEET UNDER - Four stars

What: Alan Ball's comedy-drama about life and death at a Los Angeles funeral home.

Where: HBO.

When: 9 p.m. Sundays; also Tuesdays, Wednesdays and Saturdays.