The show’s theme has always been the refusal to see anyone as inhuman. Illustration by Mikkel Sommer

Nearly every moment of the fourth season of “Orange Is the New Black”—which this review discusses in full—feels refracted in a small sequence in the finale, a bubble of joy floating up through tragedy. In a flashback, Poussey Washington (Samira Wiley) is visiting friends in New York, and ends up taking an F train to Dumbo, blissful and exhausted. Sitting next to her, a white guy with dreads plays a steel drum. An Asian mother falls asleep; when her little boy opens her wallet to take some cash, Poussey catches the eye of a middle-aged man in a turban. They smile, sharing the secret. Poussey watches Wall Street suits offering a flask to two girls, then gazes at an older black woman reading Michael Chabon, an interracial couple kissing, a pregnant woman, some jocks.

For anyone who lives in New York City, this is a familiar vision of cosmopolitan heaven—a weave of strangers, open and curious. The city that Poussey gets lost in isn’t perfect. She’s a young black woman, and when her phone is stolen, and she asks for help, white men brush her off. But, for a few hours, her life is full of jittery serendipity: she meets a drag queen named Miss Crimson Tide; she sees a dopey Roots cover band; she goes to a club where participants follow instructions that flash on the wall (Kiss, Dance, Share); she ends up hitching a bike ride from a fake monk who’s a member of Improv Everywhere. It’s hell to watch, though. The subway car is the inverse of the justice system that will swallow Poussey up and, years later, kill her.

The theme of “Orange Is the New Black”—a show that launched on the cusp of a TV revolution in diversity—has always been empathy, a refusal to see anyone as inhuman. But, season by season, the show has shifted, absorbing and reflecting critiques. The first season spun its ensemble around Piper Chapman, a white, well-to-do outlier who went to Litchfield Prison for smuggling drug money. In Season 2, Piper receded, and the main arc was a sharp melodrama of six black women: a villain, a heroine, a tragic victim, an object of love, a henchman, and a clown. (Those six weren’t the only black characters: there was also an elderly woman, a trans hairdresser, and a guard—such is the ensemble’s radical sprawl, which emphasizes not just diversity of characters but wild diversity within groups, including the guards.) The backstories were more varied, the ethical range broader, the jokes sharper. Last season, the show’s third, Litchfield was bought by a corporation, M.C.C., which union-busted guards and exploited inmates as sweatshop drones. The tone darkened, with a focus on the gruesome spillover of privatization—one character was raped, another put in solitary—and yet the season still managed to end in a rapturous vision of unity, with the inmates swimming together, as if baptized, in a lake.

The hardest trick for “Orange Is the New Black” has always been in balancing its humane values—sex, humor, spirituality—with candor about its harsh setting. (Too light, it’s trivializing; too heavy, it’s gloom porn.) This season, the show made a risky leap, taking structural racism as its central subject. Owing to an influx of prisoners, Litchfield is now dominated by Dominicans, whom the guards treat differently from white inmates. Piper’s attempt to exploit this distinction, by forming a community-watch program—really a cover for her attempt to squash competitors in a smuggling business—aligns her with neo-Nazis. (In a solid song cue, “Tomorrow Belongs to Me” plays over the credits.) Even in a show that thrives on rude comedy, the epithets feel uglier, the plots more violent. (Some echo the HBO men’s-prison show, “Oz.”) In the penultimate episode, there’s a cruel loss: Poussey, the heroine from Season 2, a military brat with a romantic heart, dies beneath the knee of a guard named Bayley, gasping, “I can’t breathe.”

“Someone died on your watch, Captain,” the prison warden Caputo says, self-righteously, to the dehumanizing monster whom he had left alone to oversee the callous new guards. “A human being. And you better believe we’re going to look into it—and we’re gonna be hearing many stories. Not just the story you’re telling, but many stories.” It’s as if Caputo were predicting the emergence of “Orange Is the New Black” itself. Then he punts. For the news cameras, he offers just one story: he defends the guard who killed Poussey. He doesn’t say Poussey’s name. The prison explodes, in a gorgeously filmed sequence that ends with the camera spinning and a gun pointed at a guard’s head.

In response, there was an explosion of rage and grief among some viewers online (another community that is both hell and heaven, with strangers struggling to communicate, side by side). Some observers resented the fact that the show, which has mostly white writers, had forced fans, especially African-Americans, to soak in racist violence rather than offering them a respite from it. Some were uncomfortable with echoes of real crimes. Some of the pushback was fan response to losing a beloved character—especially a black lesbian, a rarity on television—and, with her, a happy ending.

That’s not how I saw the final episodes, but then I wouldn’t. To me, Poussey’s death was an earned tragedy, resonant for reasons beyond simply “sending a message” about the Black Lives Matter movement. She died when the show became clearer about something that had always been buried within it: the irresolvable tension between that utopian subway car and the tilted, biased world surrounding it. Poussey was educated, world-travelled, and middle-class, but she died as any black inmate might, as a cipher crushed by a racist system. This season’s smartest move was to interrogate empathy rather than treating it as a cure-all. Compassion is a resource, too. Who gets it and who gets cut off?

One of the most powerful story arcs concerns a character who had once (like many of the series’s best characters) been a minor figure, a bit of a joke: Blanca, of the feral, glowering affect and the unibrow, howling in the bathroom about “Diablo.” This season we see Blanca’s backstory, a satisfyingly pungent fable about a kind Dominican caregiver working for a monstrous rich white woman. When Blanca gets fed up and takes revenge—screwing Diablo, her gardener boyfriend, in front of her boss—her eyes flash black. In prison, she turns a punishment into a protest: forced by a guard to stand on a cafeteria table, she pees herself, unafraid to trigger disgust, becoming an icon of civic resistance. It’s the same fury that lights up several other characters: Maria Ruiz, a Dominican mother whose sentence increases when Piper rats on her; the Puerto Rican Daya, once a dreamy artist, now abandoned by her guard-lover, her child lost in the foster system; and the African-American Taystee, Poussey’s cheerful, bounce-back friend, who had worked for Caputo, getting close enough to see his betrayal firsthand. Poussey’s death was a misery. It was also the story of Taystee’s radicalization, and of the day that Daya got sick of seeing the other side of things.

“Orange Is the New Black” is not the only show to fold the Black Lives Matter movement into its narrative. The sitcoms “Black-ish” and “The Carmichael Show” did cross-generational takes. “Scandal” offered a healing fable; “Empire” rudely satirized the theatre of protest. In “Orange,” this subject matter feels unavoidable, and it’s used smartly to complicate the critique of capitalism that fuelled Season 3. But, if Poussey’s death is realistic, it also casts a shadow backward. There’s a sweet scene in Season 2 in which Taystee tickles Poussey affectionately, until she gasps, “I can’t breathe.” Does that make the story deeper or just more unbearable?