Emilee Hackney was a teenager two-and-a-half weeks away from marrying an aspiring pastor in rural Appalachia when police seized the man’s phone, scrolled through his pictures and arrested him on child-pornography charges.

After that shocking episode, Hackney’s life continued to shift in unforeseen ways. She went from making sandwiches at a Subway shop while attending a local community college to starting over at Harvard University as a transfer student. While there, her life devolved into loneliness and dislocation, and she found herself trading in-person sex for money beyond the campus confines.

“I look back now and I think, Oh my gosh, I just got away by the skin of my teeth,” said Hackney, 29, author of “All That’s Unseen,” her newly released first book detailing those experiences. The title just debuted at #12 on the New York Times combined print and e-book nonfiction bestseller list.

The memoir is an account of escaping religious extremism and redefining herself apart from the mountains that raised her and the elite society to which she fled. Her life’s work became fusing her past as an eighth-generation Appalachian with her future in a broader world.

Hackney lives outside Charlottesville, Va., where she now works as an administrator in the English department at the University of Virginia. Two years ago, she married a fellow Virginian she met hiking the nearly 2,200-mile Appalachian Trail. They have a baby girl.

The author’s separation from Appalachia was a long one. The granddaughter of coal miners grew up in the southwest Virginia mountain town of Tazewell, within 50 miles of most every relative she ever had. Her parents weren’t die-hards at their Pentecostal church, but Hackney wanted to believe. Eventually, she spoke in tongues at worship services. “These sounds were coming out of my mouth,” she said. “I felt like I was on this new plane of understanding God.”

She was 14 when she met 18-year-old “Sam,” a pseudonym Hackney assigns him in the memoir. She’d been a wallflower when Sam, a high-school senior, began calling her “cutie” and “sexy.” She liked the attention. “I started waving back, putting up whichever hand wasn’t carrying my Hello Kitty lunch box,” she writes.

The two could avoid scandal inside the church, since they were just praying side by side and studying the Bible, so they spent more time there. When Sam suggested they try “domestic discipline,” allowing him to spank her when he felt she disobeyed him, she agreed. She got engaged to marry him in high school without telling her parents. The couple experienced red flags from the start, like when he confessed early on to having a crush on someone else—a 12-year-old girl.

Certain congregants encouraged Hackney to stay with Sam after his arrest, which the author said didn’t result in a trial or prison time. Amid the turmoil, she quietly sought counseling. But she couldn’t escape the church, whose members staffed the local therapy office. She was given some religious pamphlets and sent on her way.

Hackney applied to Harvard in an act of defiance, remembering how Sam once told her she could never get in. In her application essay, she wrote about how one’s direction in life is like a Subway sandwich. You choose what goes in it.

After her Ivy League acceptance, which came with a generous financial-aid package, she and her family went to Boston and spent a day riding the subway just for fun. But the reality of Harvard was harsh. In the fall of 2017, she was failing biology and struggling to connect with students who only seemed to hear her accent. “They’re like, ‘You can’t be taken seriously as a person on this campus if you have that background coming through your voice,’ ” she recalled.

When a professor made a snide comment about Southerners being stupid, she wrote a column for the school paper about southern stereotypes on campus. She joined Harvard’s Texas Club because she wanted to avoid northeast snobs, even though she didn’t have any connection to the state.

Feeling alone, she took up online dating, an experience that twisted sideways when one man who misunderstood their rendezvous offered her $100 and asked if the sum was high enough. She found she didn’t hate the exchange and joined a dating app that offered “transactional” relationships. She began a period of disembodied hookups. She became addicted to being used and using others.

“It was as if I’d maxed out my lifetime allowance of guilt, spent it up on things like how many times a day I’d prayed or whether my shirt had covered enough skin,” she writes in the book. “Now I was having sex for money, one of the most grievous sins I could have ever imagined, and I couldn’t force a single ounce of shame.”

She stopped using the site when she met a boyfriend at Harvard. He recommended she take a personal essay class taught by Michael Pollan, author of nonfiction books including “The Omnivore’s Dilemma” and this year’s “A World Appears.” She applied and was selected to enroll. Her first assignment: Write about a food item with personal meaning. She chose tomatoes, which grew in every garden back home. “That innocuous little essay untangled some aching knot inside me,” she writes.

In class, Hackney could be reserved, Pollan recalled. “Imagine coming from where she did and meeting your typical prep school-educated Harvard student—they’re incredibly slick and adept in class,” he said.

But on the page, she was bold, challenging preconceived notions of Appalachia. Struck by her talent, Pollan introduced her to his book agent and editor. “I hope a lot of those students read this book, and the faculty [at Harvard], too,” he said.

Hackney wrote her book against the specter of another: “Hillbilly Elegy,” the 2016 bestselling memoir invoking Appalachian values by current Vice President JD Vance, who grew up outside that region in Middletown, Ohio.

“I was disappointed that ‘Hillbilly Elegy,’ which is perhaps the most well-known Appalachian memoir, was written by someone who is arguably not even Appalachian, seems to actively disdain Appalachia and asserts that his own negative experiences indicate the entire Appalachian culture is ‘in crisis,’ ” Hackney said.

The vice president declined to comment.

Hackney, now writing a book about her monthslong trek on the Appalachian Trail following the death of her father, doesn’t feel entirely at home in those mountains today. The code of Appalachia, she said, is that you only belong if you stay. She senses the quiet judgment for not moving back. “Just by that one action of leaving, I’m out forever now,” she said. “I will never be a part of this place again like I once was.”