Forty years ago this summer, the American actor Nick Nolte commenced his film career with a forgettable low-budget, biker movie called “Electra Glide in Blue” where he played a hippie (for which he wasn't even credited).

From such an unlikely and humble beginning, Nolte became one of the greatest movie stars of the late 20th century, although he never quite ascended to the lofty levels of acclaim enjoyed by contemporaries like Robert DeNiro, Al Pacino and Jack Nicholson.

Over an uneven multi-decade career, Nolte, now 72, has starred in dozens of films ranging from comedies like “48 Hours” to thrillers like “Cape Fear” to melodramas like “The Prince of Tides.” But Nolte’s greatest performance might have been forgotten by the movie-going public.

In the spring of 1990, Nolte appeared in a police/crime saga directed by Sidney Lumet called “Q&A,” which weaved a complex tale of violence, racism, corruption, drugs and sex in contemporary New York City.

The character Nolte played in this excellent (but largely overlooked) film -- NYPD Lt. Mike Brennan – ranks as my all-time favorite character in U.S. cinematic history.

Granted, "Brennan" will never be mentioned among such legendary portrayals as DeNiro's 'Travis Bickel," Pacino's "Michael Corleone," or Marlon Brando's "Terry Malloy," but, for my money, Nolte's "Brennan" is the most compelling, mesmerizing and even frightening figure ever seen on the silver screen.

Nolte -- who gained at least 40 pounds, dyed his hair reddish-brown and grew a wildly luxuriant mustache for the role --  essentially portrays a remorseless sadistic monster and a proto-fascist who happens to wear a badge and ostensibly represents the forces of law and order.

But Mike Brennan is in reality a bloodthirsty killer, cheerfully racist, utterly devoid of morals, effortlessly profane and corrupt beyond belief.

However, in a testament to Nolte’s extraordinary acting skills, he does not play Brennan as a one-dimensional "villain," nor does he come across as an invincible "super-cop." Quite the contrary.

With his passable New York Irish accent and the unusual timbre of his voice, Nolte’s "Brennan" actually comes across as charming, the type of appealing Irishman who spins wonderful tales, tells jokes and slaps everyone in the back down at your favorite after-work pub. (Indeed, with his sparkling blue eyes, Brennan even resembles a giant leprechaun).

But beneath that seemingly attractive and charismatic exterior, lies the beating black heart of a man who has gone so far over the edge into depravity that he is no longer even a human being.

Overall, “Q&A” tells a rather convoluted story with many sub-plots, but the saga of Mike Brennan (and everything he represents) forms the dark, disturbing core of the film. The very first scene shows Brennan shooting a Puerto Rican drug dealer in an alley in Harlem, then manipulates the evidence to suggest the murder resulted from self-defense. This seemingly mundane killing sparks a tidal-wave of revelations about deep-seated corruption that stretches all the way from the ghetto to the Police Commissioner’s office.

The movie was based on a book by the same name written by former New York Judge Edwin Torres who likely dealt with many “Brennans” and created a fictional composite of several Irish beat cops and detectives.

Brennan’s Irish ethnicity is not an arbitrary literary device either -- the detective is a proud Celt whose fondest wish in life (aside from receiving as many payoffs as possible) is to re-establish the mythical New York City of his youth, a world where every ethnic and racial group knew their place in society and remained frozen in place there.

“Q&A” portrays New York City as a place of “tribals” where each group is hopelessly pitted against each other in an endless, and futile battle for supremacy.

A man like Brennan simply cannot abide by change – so he reacts to dramatic shifts in demography and cultural values by sinking deeper into the bottle, his own venal greed as well as his bottomless reservoir of hate.

Brennan has also deluded himself into thinking that he is “defending” old-fashioned values and explicitly declares that the “enemies” of society are minority groups like black and Hispanic criminals, Jewish judges and lawyers, and homosexuals, among others.

In one of his most powerful soliloquies, Brennan basically defends his brutality and his very raison d’être, while discussing another police officer he knew: “I mean, he knew there were animals out there! He knew there was a line the n_ggers, the sp_cs, the junkies, the f_ggots had to cross to get into people's throats. He was that line. I am that line. And the f_cking judges and Jew lawyers, Aldermen and g_inea DAs are raking it in. We take a f_cking hamburger and it's goodbye badge, gun and pension. All the time, it's our life that's on the line. It's our widows and our orphans!”

But the film also suggests some strange underpinnings to Brennan’s disturbing character -- he seems to have no friends and likely no wife, children nor even lovers. There are some strong suggestions that Brennan is a closeted homosexual (which might explain his self-hatred and violence against other homosexuals). We never see his “personal life” if indeed he has one -- rather, Brennan seems hopelessly devoted to his job (that is, his real job as an alleged guardian of law and order, as well as a thief, killer and enabler of criminality among the city’s vast demi-monde).

Lumet, who made a number of other movies with similar dark New York City-centric themes, including “Serpico,” “Dog Day Afternoon” and “Prince of the City,” probably filmed “Q&A” too late in his career. By the early 1990s, crime and violence in New York City had peaked and, later, under the leadership of Mayor Rudolph Giuliani, crime would plummet to previously unprecedented levels (a scenario that would have been unthinkable during the worst days of the 1970s).

Had “Q&A” been filmed and released in, say, 1971 or 1972, -- that is, during the era of “The Godfather” and “French Connection,” and real-life police corruption scandals in New York, it (and the character of Mike Brennan) might have had a much greater impact on pop culture.

After its April 1990 release, most critics praised the film and particularly Nolte’s unforgettable performance.

Hal Hinson of the Washington Post wrote: "[Nolte] doesn't flinch in the least from his character's unsavoriness; instead he seems to glory in his crumpled suits and unwashed hair, as if they were a kind of spiritual corollary. Nolte gives Brennan a kind of monumental brutishness -- he makes him seem utterly indomitable."

Similarly, David Ansen of Newsweek, gushed: "Nolte, with a big paunch and a walrus mustache, is a truly dangerous presence here; he uses his threatening body and a high, strained voice to stunning, scary effect. Like the movie, Nolte really gets in your face and, for a long time afterwards, sticks in you craw."

Finally, Vincent Canby of the New York Times described Brennan as “seriously sick. He's so unaware of himself, and of the world he inhabits, that he can seem a figure of crazy pathos when he says of the New York City he knows… [But] Mike Brennan is not a cause of the malaise … He's a symptom.”

I would agree with all the aforementioned passages, however I would add that Brennan is the ultimate modern American urban warrior anti-hero, the very manifestation of everything that has gone wrong in the post-war era of the U.S.