Two of the three new episodes of “Black Mirror” — the sci-fi-inflected drama anthology whose fifth season dropped on Netflix June 5 — are fine, if only fitfully interesting. The ideas in “Striking Vipers” (about an immersive video game that allows two friends to play out their relationship in another realm) and “Smithereens” (about a rideshare driver who takes a social-network employee hostage) are constrained, lacking the sweep and possibility of “Black Mirror” at its best, and are expressed with a sort of pinched insistence on just delivering the viewer to the narrative twist, so that what comes before the story’s end isn’t much of a story at all. On any ranking I’d make of “Black Mirror” episodes, they would place very low.

But they pale in comparison to “Rachel, Jack and Ashley Too,” the most majestically wrongheaded installment not merely of “Black Mirror’s” run but, too, of at least the past year in prestige television. Starring Miley Cyrus as a pop star struggling to find artistic and, eventually, literal freedom, the episode (unlike its narrower counterparts this season) has about fifteen potentially fruitful topics on its mind. And it tries to serve all of them in sequence, all while building towards a tone that seems borrowed from Cyrus’s last significant TV gig, “Hannah Montana.” I had previously written that “Bandersnatch,” the interactive movie that Netflix released in December, was so poorly conceived on a story level that it risked “Black Mirror’s” credibility even as it advanced the medium in some interesting ways. “Rachel, Jack and Ashley Too,” whose legacy is likeliest to be as a curio whose music gets played at Miley-esoterica-themed drag nights, doesn’t just risk “Black Mirror’s” big reputation, but clomps onstage and lights it on fire.

Cyrus, here, plays Ashley O, a woman we meet first through her music. She performs a single whose braindead lyrics, beginning with “Hey, I’m a ho / I’m on a roll,” are dystopianly cringey, or cringeworthily dystopian. (This level of obviousness, for “Black Mirror,” is new in degree but not in substance; often, though not necessarily here, it’s part of the show’s charm.) The melody, oddly, is directly ripped from “Head Like a Hole,” Nine Inch Nails’s anthemic tribute to hatred, which comes to seem less like Swiftian Easter egg placement than as if the show preferred not to have to generate a new song and, as a bonus, wanted to make the people who remember a very famous rock band feel smart. We see Ashley O on a chat show promoting both the song and a new doll, a cutely rounded A.I. critter that bears her name and speaks in her voice.

The robotic “Ashley Too” is, for Ashley, hardly a passion project — the requisite shots of the pop star allowing her smile to fade when the camera turns off, or staring out a car window while off-duty (clichés since, at least, Britney Spears’s 2000 “Lucky” video) come within the episode’s first five minutes. But the doll is a massive treat for Rachel (Angourie Rice), an unpopular girl who idolizes Ashley out of proportion to her peers. It provides a form of solace when Ashley, whose ambivalence to fame runs up against her comically hard-driving aunt/manager (Susan Pourfar), is forced to take a hiatus from actively recording. Netflix has asked that the specific contours of this detail of the story be preserved for viewers. Suffice it to say that the future of Ashley’s career seems likely to unfold without her active consent, a drama with real-world symbolic resonances throughout recent music history, from girl group TLC having a fortune taken from them by usurious contracts, to Spears’s little-understood conservatorship, to the big business of hologram concerts, most recently floated as a cash cow for the estate of Whitney Houston.

The long-term trend of women in music presenting a show of empowerment while being financially and creatively under someone else’s control presents appealing groundwork for a show that’s made its name dreaming up a future to take on. And it would seem likely aided metatextually by a lead actress whose art form — often more potent and certainly more widely-remarked-upon than much of her actual product, including an EP released just last week — is rebellion against strictures real and perceived. But those who think that Cyrus’s provocations are as often meaninglessly chaotic as they are purposeful will find an installment of television that matches its lead’s energy: Having come up with a premise, series creator and episode writer Charlie Brooker can’t find the next beat. To borrow a phrase from Lady Gaga’s sci-fi-futurist period, this episode’s artpop could mean anything. But likelier, it means nothing at all.

“Rachel, Jack and Ashley Too” cedes much of its second half to a caper in which Rachel and her sister Jack (Madison Davenport) play a near-future version of “Spy Kids.” Facing what we’re told is a fairly grave situation and one with far-reaching implications, Rachel and Jack, aided by a sassy-talking robotic doll, pose as professional exterminators to break into the real Ashley’s home; they later drive a car into an arena where a concert is unfolding. Over an hour, we’ve moved from a familiar and dour vision of pop stardom-as-gilded cage to a sparkily surreal fantasyland that it’s hard to imagine an adult taking seriously.

Cyrus represents what little in the episode can be said to work, and what badly doesn’t. What nuance she was able to bring to even the most brutally unimaginative lines given to her human character feel sorely missed once she’s exited the narrative, not least because Ashley Too is such unpleasant company. Plugged into an outlet, Ashley Too yells “Get that fucking cable out of my ass!” Over an hour-plus running time, the mouthy-robot shtick is as charming as it sounds. This installment wants to say a lot of things at once, but has a fundamental unseriousness of tone and of approach that makes anything it might say seem not worth the effort. The time has probably come to ask if there are, really and truly, enough ideas in the tank to keep “Black Mirror” a going concern; the franchise’s notoriety will keep people watching for a while, but if audience trust withstands Ashley Too, it won’t be able to bear a hypothetical Ashley Three.

The episode is doubly a shame — first because the childish zaniness of “Rachel, Jack and Ashley Too” seems like a meaningful turning point for a show whose strength once lay in its low-fi, chilling version of a future two steps from lived reality. The second is that Cyrus, who has said the episode “tells my story in some dark and funny way,” is both doing a good job as Ashley O and has been, in real life, near the center of a decade or so in which mega-famous women in music — including contemporaries like Taylor Swift, Beyoncé, Katy Perry, Lady Gaga, and Ariana Grande — have, with varying and often evolving degrees of seeming career independence, dominated the cultural conversation.

It’s a moment, now seemingly waning, that has provided inspiration for remarkable recent films including 2018’s dream double-feature of “A Star Is Born” and “Vox Lux,” both of which played like treatises on artistic autonomy in the age of digital reproduction. “Vox Lux,” in Natalie Portman’s performance and in its storyline, seemed to address aspects of Perry’s prepackaged flair; “A Star Is Born,” with its obsession with pop purity (and, uh, its real-life female lead) was the Gaga show. And both made larger points about what it’s like to suffer and to triumph in front of an infinitely large public, an idea both timeless and timely. Chained to the rhythm of “Black Mirror’s” format, “Rachel, Jack and Ashley Too” can’t fulfill an ambition that grand. It’s too hooked to its ineptly exuberant sci-fi flourishes and tonal veers. So consumed with showing us a future that seems pointless and impossible, this episode falls vastly short of fulfilling the particular potential of its story or doing what “Black Mirror” does best. It doesn’t make real the stage Ashley occupies, with all the expectations and responsibilities it bears, or the stage of cultural history the rest of us, out in the audience, are at.