Hail Mary and holy mother of God: a double-disc Warner Home Video DVD of Prince of the City, my all-time favorite Sidney Lumet film, is “streeting” on 5.22.07.

I regard it more affectionately than all the other sublime New York Lumet films (including Dog Day Afternoon and Find Me Guilty) because it titanically reeks of coarse and odorous five-borough atmosphere in each and every frame. On top of which it may be the most deeply conflicted “moral drama” ever made — it doesn’t finally know what it’s trying to say exactly, but oh the guilt! Guilt so mucky and tortured and ambiguous mixed with loyalty among corrupt and criminal friends, and lathered with lies and confessions and magnificent New York cop-and-mafioso patter….layer upon layer of brag, bullshit, innuendo and terrible truth.

It’s also a movie that taught me one of the most valuable life lessons I’ve ever taken to heart: choose your friends carefully but once you’ve done that, stick by them forever — never rat, never flip, and never trust a prosecutor.

Based on a true story and set in the ’70s, it’s about a narcotics cop named Danny Ciello (Treat Williams) who wants to unburden himself of guilt about his reckless dishonest ways, so he decides to go undercover for the feds to uncover police corruption. At first the danger of the job excites him and he gets away with it, but eventually the feds squeeze him into ratting out his partners and friends, and before you know it the guy’s freaking and then imploding, and then on the brink of suicide.

The blue-chip cast includes Jerry Orbach (his “Gus Levy” is flat-out the best performance he’s ever given), Lindsay Crouse, Bob Balaban, Richard Foronjy, Don Billett, Kenny Marino, Carmine Caridi, Tony Page, Norman Parker, Paul Roebling, James Tolkan, Steve Inwood, Ron Maccone, Ron Karabatsos, Tony DiBenedetto, Robert Christian, Cosmo Allegretti, Michael Beckett — every character and performance is absolutely and thoroughly “New York authentic.”

It runs 167 minutes and 80% of it is about prosecutors and cops and mafiosos, sitting and pacing inside government offices talking about evidence and guilt and indictments. All wearing white shirts and ties, toughing it out and stating their cases, sipping coffee out of cheap styrofoam cups as they try to out-bluster and out-truth-talk each other.

Roger Ebert wrote nearly 26 years ago that “this is a movie that literally hinges on the issue of perjury. And Sidney Lumet and his co-writer, Jay Presson Allen, have a great deal of respect for the legal questions involved. There is a sustained scene in this movie that is one of the most spellbinding I can imagine, and it consists entirely of government lawyers debating whether a given situation justifies a charge of perjury. Rarely are ethical issues discussed in such detail in a movie, and hardly ever so effectively.”

Prince of the City acquainted me with a Thomas de Quincy passage that I’ve never forgotten: “If once a man indulges himself in murder, very soon he comes to think little of robbing; and from robbing he comes next to drinking and Sabbath-breaking, and from that to incivility and procrastination.”