It’s the second week in August and Ireland is in the throes of a record-breaking heat wave, but novelist John Boyne has made only a minor concession to the sweltering temperatures. Speaking over Zoom from his garden studio in Dublin, he raises a handheld electric fan to the computer screen: “I’ve got these things going everywhere,” he says with a laugh.

Otherwise, it’s business as usual for Boyne, who typically spends seven days a week writing in the studio, which he jokingly refers to as his “ego room.” Cheerful seafoam-green bookshelves line the walls, displaying foreign-language editions of his 20 published books. The stylish tableau is both a testament to his design sensibility (he won the Irish reality TV show competition Celebrity Home of the Year in 2019) and a reflection of the joy he takes in his work.

“I’ve never been one of those writers who says, ‘I hate writing,’ ” Boyne says. “I still love it. I can’t be not working on something or I’ll get a bit lost. If I’m here for a couple hours doing something and I feel like I’ve got a good day’s work, I’m buzzing.”

In 2004, Boyne put in two and a half days’ work that changed his life. Over the course of 60 sleepless hours, he wrote the first draft of The Boy in the Striped Pajamas, the blockbuster YA novel that has been adapted into a film, a ballet, and an opera. It began, he explains, with a mental image of two boys sitting on opposite sides of a fence. He knew the fence was at Auschwitz, and that the boys—Bruno, the son of the camp commandant, and Shmuel, a Jewish prisoner—would hold hands as they met their tragic fate at the novel’s end.

From there, Boyne says, the story “just poured out of me. It became almost automatic writing by the third morning—it was kind of extraordinary.”

A graduate of the creative writing program at the University of East Anglia in Norwich, England, Boyne wanted to be an author since childhood. “There was never a backup plan for me,” he says. “It’s the only thing I ever wanted.” Though he met his goal of publishing his debut novel—2000’s The Thief of Time—before turning 30, his first three books “collectively sold about eight copies,” he jokes. Everything changed when The Boy in the Striped Pajamas was published in 2006.

“It took off so quickly all around the world,” he recalls. “Every day my agent would be in touch with another deal from another country. I’m very lucky, because I have plenty of friends who haven’t gotten that magic moment, and it’s not a reflection of the quality of their work.”

Boyne’s new novel, All the Broken Places (Viking/Dorman, Nov.), harkens back to his magic moment. Picking up where The Boy in the Striped Pajamas left off, it follows Bruno’s older sister, Gretel, as she struggles to come to terms with her brother’s death and her own complicity in the Holocaust.

Though Boyne had the idea to tell Gretel’s story only days after finishing the first draft of The Boy in the Striped Pajamas, he didn’t think he would get around to writing the novel until the end of his career. “I thought it would be a nice one to go out on,” he says. But then Covid-19 lockdowns happened, and “it felt like the right time to do it.” He also chose to set the novel in the present, when Gretel is 91 years old and living in London. “I wanted to remind readers that this isn’t something that happened in Tudor times,” he explains.

All the Broken Places interweaves the contemporary story of Gretel’s escalating involvement with a troubled young family that moves downstairs from her apartment with vignettes from her past. In 1946 Paris, she and her mother attempt to restart their lives under false identities. In 1950s Australia, a confrontation with an ominous figure from her Auschwitz days sparks Gretel’s flight to England, where she embarks on an ill-fated love affair.

Tonally and structurally, All the Broken Places is a significant departure from its slim and fable-like predecessor, more reminiscent of the “big, epic, Dickensian storytelling” Boyne associates with his literary hero, John Irving. (At the mention of Irving’s name, Boyne proudly displays his two tattoos: on his right forearm, the phrase “wave after wave,” a reference to Kate Bush’s song cycle The Ninth Wave; on his left, the last line of The World According to Garp: “We are all terminal cases.”) Though he can’t think of another instance in which the sequel to a YA novel has been published by an adult imprint, Boyne, who has written 15 books for adults and six for young readers, has always based the age of his target audience for each book on the age of its protagonist.

While Boyne based Bruno on his younger self, he found it “quite comfortable” to step into Gretel’s shoes—perhaps, he says, “because I’d been thinking about her for so long. I don’t think I would have started it unless, subconsciously, I knew I was ready to find her voice within the book. The one thing I didn’t know is how she would really feel about it—about her family’s part in the Holocaust and about her part in it. I know as a writer that you only discover that by writing it. You have to put her into actual scenes—to give her dialogue and have her meet other people—to find out.”

What Boyne found as he wrote All the Broken Places is that Gretel is a more “contemplative” and less “combative” character than he initially thought. “She doesn’t feel guilty of a crime,” he says, “but she does know that every piece of information that could have been given to the Allies could have helped somebody out, and by not doing that, she’s disgraced herself and her life.”

Boyne insists, however, that raising questions about how responsible the children of Nazi higher-ups should be for their parents’ actions does not necessarily mean sympathizing with them—a charge that has been levied by critics of The Boy in the Striped Pajamas, who claim that by telling the story from Bruno’s perspective, Boyne detracted from the horrors of the Holocaust and the death of Shmuel.

“I’m always a little surprised,” Boyne says, “when people say that they feel they’re only supposed to feel sorry for Bruno. It’s not a description of the ending of the book that I recognize.”

Boyne deleted his Twitter account after his most recent YA novel, 2019’s My Brother’s Name Is Jessica, sparked a social media backlash over its representation of trans people—a controversy heightened by an Irish Times op-ed in which he expressed support for trans rights while rejecting the word cis as an “unwanted term” forced by one person on to another. “Life is so much more peaceful and less anxious” after getting off Twitter, he says. “Everybody has such entrenched opinions, and everybody demonizes everybody else. I’ve been demonized several times and I’m just a guy who writes novels; I’m not some awful being.”

Though he admits to being “more guarded” than he was when The Boy in the Striped Pajamas came out, Boyne hopes that people don’t criticize the new novel simply because of its existence. “I’ve tried to write something interesting and empathetic, with a character people can read about and think about,” he says. “Gretel’s not the most likable character, but she’s not a dislikable character either. It’s up to the reader to get to the end and discover how they feel about this woman and what she’s gone through—the mistakes she’s made and how she’s tried to right things.”

“That’s just a life,” Boyne continues. “We’re not saints and we’re not sinners, most of us. We’re somewhere in the middle ground, and so is she.”