"I’m always working on something,” says Kate Atkinson, whose new novel, Transcription, will be published in September by Little, Brown. “It’s really tedious, but I’ll never stop. If I stop I’ll never start up again.”

It’s 4 p.m. and Atkinson, who’s published 11 books, including the international bestseller Life After Life, has just finished work for the day, clocking up another six pages of the book that will follow Transcription. “It’s a revolting comparison,” Atkinson says, “but it is a bit like a chicken, with the eggs in the oviduct.” In another life, years ago, she kept chickens. They all died. “You start at the very end with the egg in its shell, and before that it’s the egg without its shell, and then it’s the yolk, and it gets smaller and smaller and you’ve got this queue of eggs waiting to be laid.”

Atkinson laughs, an explosion of mirth tinged with a hint of wickedness. “Novels for me are a bit like that,” she adds. “You can feel there’s a small one at the end of the queue, and they get bigger as they get nearer. And by the time you’re getting to the end of the novel you’re writing, the next one is really pushing.”

Revolting or not, it’s an apt comparison. Atkinson’s first book, Behind the Scenes at the Museum, won the 1995 Whitbread First Novel Award. Since then, she has published a book, steady as she goes, every two to three years.

Transcription appeared in the queue roughly four years ago, as Atkinson was researching A God in Ruins, a companion novel to Life After Life. One day while snooping in the U.K.’s National Archives, Atkinson came across a declassified release from MI5, England’s domestic counterintelligence and security agency, about WWII British spy Jack King. The release revealed King’s real name—Eric Roberts—and his perfectly dull nine-to-five job: bank clerk. In that moment, Atkinson says she told herself, “I have to write about this.” Her interest quickly fell on the spy’s transcriber, and she began to imagine the complex relationship this young woman would develop with the King figure, named Godfrey Toby in the book, whose inscrutability creates a suspicion of double dealings.

With A God in Ruins in production, Atkinson began Transcription. Like her two previous books, the novel would deal with WWII, only more obliquely. “I’d done the blitz,” Atkinson says. While Transcription doesn’t focus directly on the war, it still bears the author’s trademark temporal Gordian knots. The novel begins in 1981, when Ronald Reagan, Margaret Thatcher, and Mikhail Gorbachev ruled the globe, but it’s mostly set in 1940 and 1950.

“I find the postwar period particularly interesting,” Atkinson says. “A country that feels defeated—bankrupt and filthy—and an exhausted populace, just shabby.”

Atkinson’s heroine is the plucky Londoner Juliet Armstrong, recruited at the age of 18 into MI5. Juliet begins her life in espionage in a flat in Dolphin Square in 1940, transcribing secretly recorded conversations. In the bugged neighboring flat, Godfrey Toby, posing as a Gestapo agent, meets a dreary bunch of British Nazi sympathizers who pass on intelligence about Jews and other enemies of the Führer.

To Juliet, the conversations are either difficult to discern or achingly dull. Her transcriptions, amusingly, are full of notes like “biscuit interval” and “inaudible.” But she gains the trust of MI5, and is soon promoted to full-fledged spy.

Juliet’s secret service becomes far more exciting when she’s running around London. She must infiltrate the Right Club, an insidious group of well-connected fascists, befriend its female members, and steal its membership ledger. As she gets closer to success and real danger, the mission takes a deadly turn.

A decade later, Juliet has put her clandestine activities behind her to focus on her job with the BBC. But, as Atkinson knows better than most, history is never as far behind us as we would like to believe.

Atkinson thinks she would have made a good spy. “I like secrets,” she says. “Although I’m not very good at keeping them.” Like her heroine, she thinks of herself as a voyeur and claims to have felt this way almost since birth. “Everything is a foreign country to me,” she says.

Atkinson was born in 1951 in the ancient walled city of York, in Northern England. In 1995, she moved 200 miles north to Edinburgh, Scotland’s medieval capital, where she lives in an Edwardian house that she endeavors to return to “what it would have looked like in an ideal world,” she says. By “ideal world” she means the beginning of the 20th century, an irony not lost on the author of extremely popular historical fiction.

Inside her historic home, Atkinson is surrounded by the past. The Victorian wallpaper is William Morris, a woodland scene with deer. Heat rises from cast-iron radiators popular in the 18th century. A sofa is draped with a grey toile de Jouy pattern dating to the 16th century. The curtains on the windows are lace. A wooden case containing stuffed Indian birds hangs on one wall. Lamps are topped with shades made by Downton Abbey’s art department; they may not be old, but they look it. “I completely forget we’re actually in the 21st century,” she says.

Atkinson rises around 5 a.m. each morning and puts the Bialetti on the hob for her first cup of strong coffee. Before writing, she spends a few hours “faffing about,” doing yoga, organizing her life, and making more coffee. “I’d probably give up one of my children—no, both, I couldn’t choose—rather than coffee,” she says.

Atkinson dives into the writing by 9:30 a.m. at the latest, working in one of two rooms, sitting on one of her two sofas, feet up. “I need to be in a very relaxed position,” she says, due to an uncooperative back. “Very much Elizabeth B. Browning style.”

For Atkinson, most days are writing days—five or six per week. She stays at it for eight to nine hours before her “brain packs up,” she says. “Nobody’s holding a gun to my head to write. It’s a job—a job I’ll be doing until I drop in harness.”

When asked how long it usually takes her to write a novel, Atkinson speaks about quarters. The last quarter is the easiest, a race to the end. “I speed up phenomenally,” she says, “because I know what I’m doing by then.” The first is simultaneous writing and revision, moving both forward and back. “I rewrite all the time,” she says. “Every day. Every day. If you looked at my process, as we call it, you would think, ‘God, this woman is faffing.’ But it helps me think. It’s not that the first quarter, half, three-quarters is more difficult—it’s just that it’s much, much slower. Transcription was very slow in the middle. I kept changing the time structure, rejigging where chapters were and that took a lot of time. By the end, I knew where I was going and what I was getting to and knew I was going to enjoy writing the last quarter.”

When Atkinson reaches the end of that heavily revised initial draft, she says that it’s sound, needing one or two more passes before going off to her longtime publisher (Transworld in the U.K.; Little, Brown in the U.S.). “If you locked me in a room, Rapunzel style, and gave me excellent, five-star room service, I could write a novel in less than six months,” she says.

Tomorrow and the next day, and most days after that, Atkinson will rise before dawn, take her coffee to her couch, and write until the birds outside start settling down for the night. “I always think I’ll know when it’s time for me to go,” Atkinson says, “because there won’t be any books there waiting to be written.”

Mike Harvkey is the author of In the Course of Human Events (Soft Skull, 2014) and a former deputy reviews editor at Publishers Weekly.