After introducing readers to Mona, an intelligent and empathetic but slightly lost young woman who cleans houses for a living, in her extraordinary debut novel, Pretend I’m Dead, Jen Beagin dives back into Mona’s darkly comic world with Vacuum in the Dark. Still cleaning houses for a living, poor Mona can’t even get through the first page of her sequel without finding something disturbing in a client’s bathroom. Luckily for her, she has her close confidante and imaginary friend, Fresh Air host Terry Gross, to keep her company.

Sure, Terry Gross is a real person, but that doesn’t stop Mona from imagining a very real friendship with a Terry that only exists in her head. Beagin herself doubts she could have written the book without Terry’s help. When Beagin worked as a house cleaner, she’d listen to Fresh Air and idly imagine Terry interviewing her about microwave-cleaning methods. So when she started writing Vacuum in the Dark and needed help exploring Mona’s interior world, Terry’s voice was the natural choice.

“When Terry showed up on the first page, it felt right immediately,” says Beagin. “It felt like a gift. Now I could write thoughts as dialogue—a huge relief. And her voice is so relaxing. And she seems so normal, you know, and wise, and sober, and yet she doesn’t seem to dull Mona’s edges.”

Terry is particularly helpful when it comes to analyzing Mona’s often questionable choices, something Mona is not interested in doing, especially when it comes to her taste in men. Mr. Disgusting (as Mona calls him), an addict and the central male figure and love interest from Pretend I’m Dead is gone, and in his place is the aptly named (again, by Mona) Mr. Dark.

Dark is so compelling and magnetic it’s easy to see why Mona is drawn to him, even when it turns out that he’s the husband of one of her clients. Not that he’s cheating with Mona—he and the wife have an arrangement—but it’s a hairy situation that gives even Mona pause. But Dark knows just how to get under Mona’s skin, literally and figuratively.

“Part of what I wanted Dark to bring out in Mona is her weakness for good storytelling. That’s how you seduce Mona. It was how Mr. Disgusting seduced her in the first book, and it happens again with Dark, whose story is even juicier. I was also curious to see if I could write sex scenes that were sexy…There’s a lot of abuse in this book, so I wanted Mona to experience some actual pleasure, and although Dark might not be right for her in the end, he knows what he’s doing in bed.”

Even with all that pleasure going on, there’s something dark about Dark. Beagin includes two pointed scenes where dogs seem to warn Mona that Dark is bad news, and there’s no greater red flag than a dog’s distrust. But Mona, who is too smart and perceptive to fall totally under his spell, finds it difficult to turn him away when he makes her feel so good.

Kooky clients and smoldering men aside, Mona is by far the most fascinating character in her story, even if she doesn’t know it. “Mona dislikes the sound of her own voice,” says Beagin. “She was raised to be seen and not heard, and to be passive. She was rewarded for keeping quiet, playing dumb, and for serving the needs of others: cleaning, cooking, giving inappropriate back rubs, and so on. Consequently, going inward is work for her, or at least not very pleasant or natural, and it's especially difficult because her shit is so buried. Focusing on other people's problems is much easier, especially when these other people act out all over the place.”

But Mona’s disinterest in herself may not last forever. Beagin is working on a third Mona book, and despite the fact that she hasn’t quite started writing it, she plans to continue teasing Mona out of her shell. And it seems only fitting that the catalyst will not be a third central man, but a relationship with a woman. What will Terry have to say about that?

Chelsea Ennen is an editorial assistant at Kirkus Reviews.