There is a robot corollary to Chekhov’s adage about guns: If a humanlike machine is introduced alongside promises that it is really not human, it soon will be. So it is in HBO’s new drama, Westworld, loosely based on the 1973 film of the same name, created by Michael Crichton, in which robots at a Western-themed amusement park, and specifically a Yul Brynner robot, gain sentience and start killing visitors. Four episodes into Westworld, all that was sent to critics, none of the guests are dead yet but not for lack of deserving it. The new Westworld, created by married couple Jonah and Lisa Joy Nolan and the result of a long, bumpy development process, is a canny big swing for HBO: simultaneously the vast, thematically rich, plot-drenched drama full of sex and violence the network so desperately needs in the fast-approaching post–Game of Thrones era and a kind of apologia for the creepy sexual violence that has long powered the network and prestige dramas more generally. The show is promising with an asterisk, starting strong before casting about for distractions—hocus-pocus backstory, a quest, an unnecessary mythology—from its morally disturbing premise.

Westworld is set in a futuristic theme park of the same name that lets its very wealthy guests travel back to the past. For $40,000 a trip, guests in bespoke cowboy duds are deposited in a vast Western theme park. The park, situated on a real piece of desert, is a choose-your-own-adventure: Guests are given no instructions but plunked into a frontier town, where they can head to the bar cum bordello—or let one of the park’s 2,000 “hosts,” extremely lifelike mechanical beings who are capable of improvising and bleeding, entice them into escapades. Guests can ride a horse, play cards, admire the scenery, head out of town to catch an outlaw, have sex with a whore, stab, murder, or rape. The hosts can be temporarily killed, both by each other and by the guests, but they cannot harm the guests or even a fly. (One saunters across a host’s eyeball, unslapped, in the series’ opening sequence.) The bullet-ridden, shotgun-blasted, flayed, and otherwise beaten-down hosts are regularly scurried out of Westworld at nightfall, fixed up, and then returned, like wind-up toys with dreams, trapped in a torture chamber.

Guests are under no compulsion to misbehave, but the logic of the world is similar to that of a perfectly realized first-person shooter game: There is plenty of incentive to do your worst. Why else are you there? The guests may be human, but they are reliably inhumane and, in the monotony of their casual brutality, dull. Some hosts are programmed to encourage this, enticing guests into sex and violence. The host Maeve (Thandie Newton), for example, the madam at the saloon in town, pimps out herself and her charges, soothing nervous guests with assurance that here they can do anything they want. She is nonetheless regularly a victim of the cataclysms of violence that turn the bar into a crime scene. The host Dolores (Evan Rachel Wood), on the other hand, is a fresh-faced farm girl whose innocence is her appeal. Her regular storyline has her witnessing the murder of her parents and then being sexually assaulted by, depending on the day, a group of outlaws that includes guests and hosts or sometimes the Man in Black (Ed Harris), a regular guest and vicious sociopath.

All of the action in Westworld is programmed and overseen by a group of professionals using technology seemingly borrowed from Jurassic Park. Dozens of employees sit in a command center around a digital projection of the park, closely monitoring everything and yet somehow, one presumes, missing their charges’, be they raptors or robots, newfangled ability to hunt people. Westworld’s creator is the eerie Dr. Robert Ford (Anthony Hopkins), who has been with the project from the start and insists the hosts are inhuman, while vastly preferring their company. Most of Ford’s day-to-day responsibilities have been delegated to the gentle-seeming Bernard (Jeffrey Wright), who is in charge of programming and has sad reasons to countenance the possibility of real A.I. Safety, finance, and damage control are the domain of the rigid Theresa, played by Borgen’s Sidse Babett Knudsen, slightly miscast here as tough.

As the show begins, Ford has accidentally introduced—or at least Ford claims it was accidental—a line of code that causes a glitch in the hosts. A small number of them begin behaving strangely, hearing voices and having unprogrammed impulses and ideas, an adaptive mistake that turns out to be contagious. (For a show about the high tech, Westworld is mercifully uninterested in the details: The hosts seem to be made by a super glue gun and then dipped into white chocolate, emerging like a Vitruvian Man popsicle that can pass the Turing test.) The mistake allows the hosts’ access to their past experiences, essentially giving them memories, which, without exception, are full of trauma, tragedy, brutality, and, if the host is female, endless rape. The hosts have been protected from the horror done to them only by their ability to forget, which has kept them inhuman but content. But now Westworld is populated by 2,000 abuse victims and survivors, finally waking up.

Westworld is a kind of grim scrim on television itself, where the storylines demanded by guests are not so different from storylines demanded by an audience, who always wants action. Westworld employs a man whose job it is to come up with future storylines, who is always playing to the lowest common denominator, with copious sex and ultra-violence. Westworld itself does not feature very much graphic sex. There is an occasional glimpse of sex—the rapes are generally unfilmed—but the whole setup is so deeply icky it can’t be fun: How can one consent, when one is programmed? If the guests are not all rapists, it’s only because they think they are doing it with a lifelike doll. Ironically, it seems that the gratuitous nudity of real actresses is only too distasteful to be belabored when these actresses are playing robots. But what the show lacks in sex, it makes up for in violence. The hosts can’t die, which means no matter what is done to them, they are better off than humans. But because they can’t kill guests (yet, anyway), the action sequences all have predictable outcomes, if unpredictable executions. As Harris’ Man in Black goes on killing sprees, the results are never in doubt, and so not nearly as exciting as the show seems to want them to be.

Westworld’s first episode is very strong, and its second nearly as good. It swiftly builds a world built on a deeply disturbing power dynamic that could make a decent metaphor for just about anything you choose. And then it backs away. Starting in the third episode, it’s as if Westworld’s writers lost faith that a theme park run by ethically twisted tech visionaries and full of A.I. with PTSD and humans who checked their morality at home is enough to power a TV show. Having achieved nuclear fusion, they abandon it for a backup generator, focusing on a needless mythology and quest narratives swiped from Lost’s discarded ideas board.

We suddenly learn about Arnold, Ford’s long-forgotten co-creator (a character almost surely created after the first episode had been written, if not filmed), who wanted to make fully sentient life but eventually died inside the park and whose code may be responsible for the glitches. Ed Harris’ Man in Black becomes fixated on a “maze,” a game within the game, that has something to do with Arnold and has a variety of other characters who were previously engaged in more interesting storylines hallucinating a maze straight out of the funny pages. All of this is much less uncomfortable than almost everything else happening in Westworld, but it is also far less original and gripping. Like the creators of Westworld, the creators of Westworld seem hesitant to fully grapple with the ethical hornets’ nest they have created. It would be worth the sting.