Fancy a Dangerous Liaisons-styledelicacy? Rachel Hulin’s epistolary debut features some lip-smacking secrets between brother and sister.

“I love epistolary novels,” says Hulin, author of Hey Harry, Hey Matilda. “I always try to think about how to get that voyeuristic voice without letters...but it just feels like you’re not getting in there. I really want to be in someone’s head. I want to feel like you know this person deeply and you know their secrets.”

Matilda and Harry Goodman have some good ones: she, an underemployed Brooklyn-based wedding photographer, told her boyfriend that her twin died tragically. (She cordially requests Harry pretend to be a cousin at an upcoming family function.) He, an untenured English professor at a small liberal arts college, is having a potentially career-ending affair with a privileged hippie undergrad named Vivian Remember Parker-Hall.

“I’m very interested in twins because, as a classic artist type, I’m both an over-sharer and very guarded,” Hulin says. “I don’t have a lot of relationships that are super intimate, in terms of people knowing all my secrets, and if you grow up with a twin you can’t hide anything. At the crux of what is interesting to me about Harry and Matilda is their complete acceptance of each other, forever, for everything.”

As told through their personal emails, Hey Harry, Hey Matilda chronicles the charming, codependent fraternal twins’ attempt to make their way in the world as artists and adults. Over the course of one year, they exchange diagrams and dilemmas, poetry and prompts:

“By the way, what was the most painful moment of your twenties?” Hulin writes, as Matilda, to Harry.

“Hey Mat,” Harry replies. “Probably when I confessed to Dad that I was doing too many drugs at college and he asked me for the number of my dealer. So that he could ‘take that cocaine finally.’ That was disappointing. You?”

Hulin is a writer and photographer whose pictorial work is represented by the ClampArt Gallery in Chelsea. She is a longtime photo editor (Rolling Stone, Radar Magazine, Nerve.com), photography critic (The Photography Post, which she co-founded), and personal essayist (The Daily Beast, Huffington Post, etc.). She is the author of the photography book Flying Henry and lives with her husband and two children in Providence, Rhode Island.

“I was a lot like Matilda,” says Hulin, who built her career in New York, “—really brave and ballsy and, at the same time, totally self-defeating, totally self-destructive in all the obvious ways.”

The Matilda character got her start in a blog Hulin created to channel her experience as a female artist in the city. Then came Harry.

“In a way he’s just a foil for her,” she says. “At the beginning I wondered, is he actually just part of her? That’s why he’s her twin—she needed someone to talk to—a rational voice. She says all the things you’re not supposed to say, and he talks her down.”

As cool, collected Harry cautions his sister near the narrative’s beginning:

“Be careful about how much you dwell on the future. You’re better off creating a narrative of the present,” Hulin writes.

However, as Harry plunges deeper into his affair—and scandal begets scandal—the siblings’ roles reverse.

“Jesus, Harry, and I thought I was the fucked-up one, driving into traffic and almost dying, but that was nothing,” Hulin writes. “You’re in a goddamned pickle, friend. Come to me in Brooklyn. We’ll dye your hair black, too, while we hide from the law. We’ll have us a time...”

Ultimately, when Hulin created an Instagram account (@heyharryheymatilda) to present the forthcoming novel, it was Matilda to whom fans wrote for advice.

“People were emailing Matilda with questions about their creative life and it blew my mind,” says Hulin, who paired her photography with snippets from the manuscript, garnering thousands of followers. “I got emails like, ‘Dear Matilda, I want to live my true life but I feel I’m living a lie—can you tell me how to be myself?’ Unbelievably poignant, beautiful things. That, so far, has been the best thing that has come out of this.

“Although Matilda couldn’t answer them beautifully—I’m no Heather Havrilesky—I loved it,” she says. “I felt that she was attracting all the artists in a quandary, and I really wanted to help.”

Megan Labrise writes “Field Notes” and features for Kirkus Reviews.