The author of “Cat Person” has a new book out. It’s full of sex and dark as hell.

Kristen Roupenian’s first short story collection is a mixed bag with tons of potential.

At the tail end of 2017, the US was convulsing with story after story of sexual violence and abuses of power. Every week, another powerful man was being accused of sexual assault or harassment or misconduct; every week, another unmissable story ricocheted around the internet with stories about sexual encounters that were coerced or forced or violent or horrifying.

And in the midst of that peculiar atmosphere, a short story went wildly viral.

It was a story about the sad and blurry middle ground between sex that is coerced by a predator and sex that is coerced by social expectations. It concerned a naive 20-year-old college girl who goes on a date with an older man, then realizes she does not want to have sex with him at the exact moment that it becomes socially impossible to back out of the encounter gracefully; she goes on to have some terrible, regrettable sex with him as a result. The story was written by a relatively unknown author named Kristen Roupenian, and its title was “Cat Person.”

Short stories don’t usually go viral the way “Cat Person” did. Probably the last time a short story circulated with such feverish avidity was in 1948, when Shirley Jackson published “The Lottery” in the New Yorker, and inspired what was then “the most mail the magazine had ever received in response to a work of fiction.”

“Cat Person” was the second-most-emailed page on the New Yorker’s website in 2017 — and it was published on December 11, meaning it had less than a month to reach that status. It was proclaimed an emblem of the times, a story that finally put into words what it feels like to be a young woman having sex that you absolutely do not want to have, seeing no way out, and feeling that you can blame no one but yourself for it.

Roupenian was taken aback by all the attention — in an essay published by the New Yorker last week, she described the response to “Cat Person” as feeling “annihilating” — but nonetheless, she parlayed the story’s success into a reported seven-figure, two-book deal. And the first of those two books, a short story collection titled You Know You Want This, is out now.

Does it live up to “Cat Person”? Not quite. You Know You Want This is not a great book. It’s uneven, and it wants to shock more than it succeeds in shocking. But it’s never boring — and it reeks of potential.

A lot of Roupenian’s stories are about monsters. They’re less interesting than her stories about people.

“Cat Person” appears in You Know You Want This, but it is in many ways an outlier. There are thematic throughlines: Most of the stories in this collection are concerned with questions of power and consent, just like “Cat Person.” But unlike “Cat Person,” which earned acclaim for its protagonist’s everygirl verisimilitude, most of the stories in You Know You Want This are narrated by monsters.

In “Bad Boy,” the narrator is a couple who get off on degrading their unlucky male friend. (“Bad boy, we said softly as we left him. Look at what you’ve done.” ) In “Sardines,” the protagonist is a divorced mother who fantasizes about bloody revenge on her husband’s new girlfriend: “swapping the lube in the girlfriend’s bedroom drawer with superglue, tying her down and tattooing SLUT across her face.” There’s a story where the narrator keeps a man locked in her basement, cutting him again and again so that she can use his blood for dark magic; there’s one where the protagonist is driven by a pathological desire to bite people.

Conventional wisdom has it that monsters are more interesting to read about than regular people, but that’s not the case here. Roupenian’s monsters are showily vile, all grotesque imagery (“her eyes were blue marbles and her dried lips had pulled high up over her teeth”), and every line is slick with shame and sadism (“I saw how, despite the care I’d taken, the newest cuts were still raw, weeping through the bandages”). The whole book is just panting with the desire to shock — but because all the grotesquery and the sadism isn’t emotionally grounded in a psychologically coherent character or set of ideas, the shock doesn’t land. I felt the effort behind it, but I was never quite convinced.

In contrast, the hapless protagonist of “Cat Person,” Margot, is a deeply convincing character, petty and insecure and narcissistic and also profoundly vulnerable. It’s her vulnerability that makes her so compelling: When I read the story, I kept seeing red flags rise up in the background as Margot began her ill-fated flirtation with the older and controlling Robert, and every time she ignored them, I wanted more strongly to intervene, to protect her, to get her out of there before the inevitable explosion. And Margot’s vulnerability is able to land because she feels so much like the kind of flighty but basically decent 20-year-old girls who fill college campuses across the country. You know Margot; you recognize her.

Perhaps that’s why the only story in You Know You Want This that approaches the level of “Cat Person” is “Nice Guy,” a 50-page screed told from the point of view of self-proclaimed nice guy Ted. Like most of Roupenian’s other protagonists, Ted is a sadistic monster (“By the time he was 35, the only way Ted could get hard and remain so for the duration of sexual intercourse was to pretend that his dick was a knife, and the woman he was fucking was stabbing herself with it,” the story begins), but unlike many of them, Ted is a recognizable sadistic monster with a coherent inner life.

Ted is the guy who weaponizes his apparent harmlessness to acquire and then discard women who he fully acknowledges are out of his league. He’s the guy who unironically uses the term “friend zone.” He’s the guy who congratulates himself for being a good friend to women, when in fact he is only befriending them because he wants to sleep with them, and he doesn’t really consider them to be fully human. He is a Nice Guy.

Ted and Margot are such vivid and compelling character portraits that they succeed in doing what the rest of this collection is trying so hard to do: They are actually shocking. When I read “Cat Person” and “Nice Guy,” I felt an electric jolt of recognition: Oh, that’s what that thing is, that thing I’ve experienced and have never been able to explain, that’s exactly what it is. When Roupenian leans into her ability to explore and explode modern archetypes like this, she’s a breathtakingly exhilarating force.

But for most of You Know You Want This, Roupenian is not leaning into that ability. Instead, she seems to be experimenting, like a dutiful student: “Here is my Angela Carter pastiche. Here is my Mary Gaitskill pastiche.” In general, there’s something slightly unformed about the book, as though it’s being written by someone who doesn’t yet have full control of her powers and isn’t even quite sure what her powers are.

That’s what you might expect from a debut short story collection by a relatively unknown writer, but it makes the runaway success of “Cat Person” feel a little unfortunate. Roupenian would have benefited from some time out of the spotlight to grow as a writer before she was catapulted into the center of the literary conversation.

Still, when You Know You Want This is good, it is very, very good. It’s an apprentice book that promises big things for the future — and it makes me very excited to see what Roupenian has in store for the second book in that two-book deal.