The Wire, which has just begun its fourth season on HBO, is surely the best TV show ever broadcast in America. This claim isn’t based on my having seen all the possible rivals for the title, but on the premise that no other program has ever done anything remotely like what this one does, namely to portray the social, political, and economic life of an American city with the scope, observational precision, and moral vision of great literature.

During its first year, it was possible to mistake The Wire for merely an unusually shrewd and vivid police drama. But the program has gotten richer and more ambitious with each season and now fits only into a category it defines by itself: the urban procedural. Its protagonist is the broken American city of Baltimore, depicted with obsessive verisimilitude and affectionate rage. Its fundamental concern is the isolation and degradation of the black underclass, a subject that has, with the exception of a blip after Hurricane Katrina, disappeared from the political radar screen. If the national conscience is ready for another sleepless night about the waste of lives in the ghetto, I expect that The Wire will be what keeps us awake.

It’s a mark of the program’s artistic courage that while drug dealing, murder, and detective work remain its bread and butter, it dares to focus Season 4 on an urban environment not ordinarily associated with prime time: an all-black middle school in West Baltimore. The show’s creator, producer, and chief writer, David Simon, has had the self-assuredness to drop the Hollywood convention of the white hero. This season, Officer McNulty, the charming rascal cop played by Dominic West, is sent to the sidelines, relegated to patrol work by his repeated defiance of mindless bureaucracy. In McNulty’s place at the center of the drama are the compelling characters of four adolescent African-American boys, played by little-known actors so preternaturally talented they don’t seem to be acting at all.

Watching the show this season feels less like observing these four children navigate their cruel world than it does like adopting them in hour-long sessions. The story begins with the boys entering eighth grade. At 12 and 13, these kids still have a chance to escape the streets. The central drama is whether “the game” of drug dealing will exert its gravitational pull on them or whether they will somehow beat the odds pointing them toward jail and violent death. The vain, troublemaking Namond, played by Julito McCullum, has a mother who wants him to follow in the footsteps of his drug-dealing father, imprisoned for multiple murders. The sweet, enterprising Randy, played by Maestro Harrell, lives with a caring foster mother who cannot protect him from the cruelties of the drug dealers or the child welfare system. Tough, mature Michael, played by Tristan Wilds, enmeshes himself with killers in order to protect his younger brother from his addicted mother’s abusive boyfriend. The most affecting of all, Dukie, played by Jermaine Crawford, comes to school hungry and dirty and lives in a home so broken we are mostly left to imagine what goes on inside. Having previewed all 13 episodes, I won’t give away what happens to them, except to say that as usual, the program reverses your expectations while breaking your heart.

Several critics have commented on The Wire’s “literary” quality. In particular, The Wire has echoes of the Victorian social panorama of Charles Dickens (who gets a mention this season, as an obscene anatomical reference). The drama repeatedly cuts from the top of Baltimore’s social structure to its bottom, from political fund-raisers in the white suburbs to the subterranean squat of a homeless junkie. As with Dickens, the excitement builds as the densely woven plot unfolds in addicting installments. The deeper connection to Dickens’ London is the program’s animating fury at the way a society robs children of their childhood. In our civilized age, we do not send 12-year-olds to work in blacking factories as the Victorians did. Today’s David Copperfield is instead warehoused at a dysfunctional school until he’s ready to sling drugs on the corner, where his odds of survival are even slimmer.

The other major theme this season is politics. A white candidate for mayor (Tommy Carcetti, played by Aiden Gillen) cynically tries to win the election by encouraging an African-American colleague on the City Council to run and split the black vote. But the ambitious Carcetti is also an idealist frustrated by the waste of lives all around him. This plot line, along with another about the venal police brass trying to manipulate crime statistics, captures the realities of government and the compound motives of politicians in a telling and subtle way. This year, The Wire’s political science is as brilliant as its sociology. It leaves The West Wing, and everything else television has tried to do on this subject, in the dust.

Before this season, The Wire won much love from critics but not much in the way of ratings. That may be less because the program leaves viewers drained and disturbed at the end of an episode than because of how hard it is to catch on to at first, thanks to the complexity of its multiple storylines and the number of characters. There is also the challenge of following the localized black dialect that the program tries to represent as faithfully as it does its other details. In the Baltimore ghetto, yo is both a salutation and the third-person singular pronoun; “feel me,” means “listen to what I’m telling you”; and the ubiquitous use of bitch has mostly replaced the N-word. The cops have their own language as well, in which a capable officer is “good police,” bystanders caught in the crossfire are “taxpayers,” and young boys up to no good are called “hoppers.” The dialogue becomes easy enough to follow after a couple of episodes, but first-time viewers should switch on the closed-captioning feature for the first hour or two so as not to miss anything.

While The Wire feels startlingly lifelike, it is not in fact a naturalistic depiction of ghetto life. That kind of realism better describes an earlier miniseries of Simon’s, The Corner, which was based on the book of the same title that he and Ed Burns wrote, set in the same Baltimore ghetto. The six-part HBO version of The Corner is nearly unwatchable, because—however true to life—the extended depiction of shrieking crack whores and broken-down junkies 10 cents short of the price of a “loosie” is too much to take. But for Simon, The Corner seems to have been a crucial life study for The Wire, a program that attains the dimensions of tragedy without being depressing.

The Wire does this by painting with brighter colors on a wider canvas and by leavening its pain with humor. The brilliant writing and bravura cast also make viewers root for dozens of rich characters, including several completely despicable ones. Everyone’s favorite survivors from earlier seasons are two truly Shakespearean figures who get a lot of play this year: the vagabond snitch Bubbles played by Andre Royo, and Omar, the gay stickup artist played by Michael K. Williams, a cold-blooded killer whose personal code involves not serving any masters other than himself and never cursing.

What ultimately makes The Wire uplifting amid the heartbreak it conveys is its embodiment of a spirit that Barack Obama calls “the audacity of hope.” It is filled with characters who should quit but don’t, not only the boys themselves but teachers, cops, ex-cops, and ex-cons who lose their hearts to them. This refusal to give up in the face of defeat is the reality of ghetto life as well. Feel me: It’s what The Wire is all about.