Orange Is the New Black” has been less a television show than a movement. The drama — Netflix’s only truly great one — burst on the scene in 2012 as a vehicle of change, both in terms of what we view as prestige television and how we think about mass incarceration in the United States. Author Piper Kerman’s book of the same name, which loosely makes up the source material for show, proved as a window into the prison system for a readership that both lived outside of it and never expected to be a part of it; Piper herself as an author and as a character in the show (played by Taylor Schilling) spends most of her time at Litchfield highlighting the differences between her and the other inmates.

It’s a frustrating reflex, but a useful one, too; in terms of educating its mostly privileged audience, “Orange Is The New Black” is the most influential show since “The Wire.” The storytelling of the show hasn’t always been even, but especially in that explosive first season, showrunner Jenji Kohan and fledgling studio Netflix found a way to capture the national conversation about diversity in casting, transgender awareness, institutional racism and sexism, and the basic injustices of the military-industrial complex in one fell swoop. Laverne Cox’s character Sophia may be single-handedly responsible for a sea change in the visibility of and conversation around transgender people; the show not only brought trans issues to the mainstream but propelled Cox to the cover of Time magazine — which, in turn, paved the way for Caitlyn Jenner to make the cover of Vanity Fair.

But at times, the significance of the show seemed to overshadow the quality of the show itself. “Orange Is The New Black”’s second and third seasons dipped the show through an extended arc of hijinks that were markedly less terrifying than the obstacles and threats of the first season. The fact that the show upturned certain conventions of the prison-exploitation genre while simultaneously maintaining its parameters was one of the reasons the show became compelling for its viewers; at the same time, prison isn’t fun, and to act as if it were commits a disservice, both to real inmates and to the audience at home.

The fourth season does not have this problem. After one season of identifying as a comedy for the Emmys and two seasons of sloppier, less poignant storytelling, this fourth season, which debuted early this morning on Netflix, is not pretending that things are funnier or more upbeat than they really are. Either by accident or design, Kohan and her team have found a way to pull the rug out from under its audience, with a sudden reminder of the horrors of mass incarceration. A few things have happened to Litchfield all at once: Privatization, an employee walkout, and a sudden influx of new inmates. It is, as the show advances, a recipe for disaster; the precious and hard-won peace at Litchfield is quickly swept away by strife between different Latina gangs and a whole host of new correctional officers, cobbled together from a veterans’ hiring program and from surplus guards down at super-max.

The new inmates are not any worse than the ones we’ve come to know, but they’re new, and that puts both the viewer and the veterans of Litchfield on guard. The imposed closeness creates an atmosphere less like a weird indoor summer camp and more like the small apartment of “A Streetcar Named Desire,” magnified to take up a whole cell block. Humanity had acquired a rosier glow in Litchfield, but in season four, the viewer is reminded of Piper’s utter despair in her first few days in the system. There is a much darker undercurrent of twisted, unshakable evil at the heart of Litchfield’s fourth season — on display from the casually cruel COs and the quarreling inmates, yes, but also in its protagonist Piper, who takes to her self-appointed identity as a criminal mastermind to further and more worrying depths. Along with administrative changes at Litchfield are a few narrative ones for the show. A lot of the flashbacks, for example, don’t explore how the character ended up in prison, but instead just examine a facet of their character. And season four introduces backstories for more than one corrections officer, which are in their own way just as tragic and twisted as the inmates’. The result is both a narrative and a kaleidoscope, as many different interpretations of the same reality try to live together under the same (probably leaking) roof.

The show is still occasionally prone to self-indulgence. Early in the season, there’s an extended and unsubtle Israel/Palestine metaphor drawn in the conflict between Black Cindy (Adrienne C. Moore) — now named Tova, after her conversion to Judaism in season three—and a new Muslim inmate, who of course ends up her roommate, trying to lay claim to the same space in an increasingly contentious living situation. It’s funny, but it’s rather stylized for what is otherwise a show that prides itself on verisimilitude, from poop to warts to menstrual blood.

But then again, the conflict might be there to toss in some comic relief in a season that slides from teetering peril to increasing ruin. Pennsatucky (Taryn Manning), whose rape last season was one of the most intense scenes the show has ever attempted, has become a stunning, vivid portrait of post-traumatic survivorship. All on her own, Manning has taken the character from insane to empathetic to infuriating and now to heartbreaking, as Pennsatucky has to live day in and day out under the supervision of a rapist who believes himself to be in love with her. In the fourth episode of the season, Pennsatucky has a quiet conversation with him that explains, calmly, that the fact that he loves her does not change what he did. It’s extraordinary for its simplicity; and in a television climate that is quick to use rape as a plot device and then discard either the victim or the memory of the crime, Pennsatucky is the embodiment of memory in the middle of a rape plot that is being pursued with astonishing grace. No wonder the show’s writers want to throw in some comedy; this is an incredible journey, but a harrowing one, too.

But if prestige drama has taught us anything — anything aside from the myriad ways to package and transport drugs — it’s that reckoning with horror is a fundamental part of being alive. In a landscape that is bleaker than ever, the stories of the Litchfield inmates continually take the viewer in a new direction, from parent-child dynamics to the economics of food stamps. There is a richness to the universe of “Orange Is the New Black,” and that’s because for the most part, it is our own. Early in the season, Brook Soso (Kimiko Glenn) stumbles into the phrase “the other one percent,” and though she doesn’t know what she’s saying, the writers surely do: Just as one percent of this country is unimaginably wealthy, another one percent of this country is incarcerated. The fourth season takes an unflinching look at the horror that human beings are capable of inside prison, but it also brings some of that weight to bear on the viewer. We are forced to consider what we are capable of making others endure, too.