A train, a Nile steamer, an airplane … Agatha Christie loved setting her stories of death on the move. And she herself loved life in motion. “Your travel life has the essence of a dream,” she wrote in her 1976 autobiography. “You are yourself, but a different self.” The travel boom of the 20th century—the British writer was born in 1890—was central to her life and work.

Many associate Christie with Devon, and particularly her birthplace of Torquay, on the south coast of England. But this idea that she was a staid English lady was basically a marketing ploy by her publishers, designed to appeal in particular to American readers. In reality, Christie came from a family of globe-trotters.

Her father was born in New York City, settling in Torquay only after marrying an English wife (Christie’s mother). There, he frittered away the family fortune. When Christie was a teenager, finances meant she couldn’t “come out” into society in New York, as her older sister had done. Instead, she was given a cut-price debutante season, traveling with her mother to Egypt’s expatriate-British community.

Christie in Egypt, 1931.

In Cairo, a 17-year-old Christie danced at balls, five nights a week, with officers from the British garrison. Christie’s mother expected her to marry a man with money, but she displayed a rather perverse attraction to excitement instead.

In 1912, she fell in love with a young man who came to woo her on his motorbike. Christie herself was addicted to speed and had even flown in a plane. (She’d been to an air show with her mother and paid £5, a huge sum, for what she described as “five minutes of ecstasy.”) The young man with the bike, Archibald Christie, was training to be a pilot, and would serve in the Royal Flying Corps in World War I.

“Your travel life has the essence of a dream.… You are yourself, but a different self.”

When Agatha and Archie were married, she took great pride in the money—initially pin money—she earned from her detective novels. Christie had always written stories for fun. It was while volunteering as a nurse in the Great War, though, that she’d learned all about the drugs and medicines that would inspire her first fictional death: a poisoning.

The Mysterious Affair at Styles came out in 1920. In 1922, Christie’s husband took a job that involved circumnavigating the globe, visiting the outposts of the British Empire in preparation for a trade fair in London. Christie went, too, using the trip to inspire her copy. “The tools of my trade are going with me,” she said in a newspaper interview—“the typewriter, notebooks, and heaps and heaps of paper.”

Christie visits the Acropolis, in Athens, 1958.

The ship upon which the couple traveled would appear in Christie’s 1924 novel The Man in the Brown Suit. This was the golden age of ocean liners, as naval ships from the war were turned to more peaceful purposes. During their South Africa layover, Christie learned to surf. She loved it. In Hawaii, she surfed so much she hurt her shoulder.

Back in England, Archie and Agatha’s marriage grew stagnant. In 1928, after divorcing him, Christie was determined to make a fresh start in life, and she set off on a solitary visit to Iraq. She wanted to see the ancient remains being discovered at Ur.

In Iraq, Christie would meet the great love of her life, the archaeologist Max Mallowan. The two were married on September 11, 1930, and in years to come he would take her on annual excavation trips to Iraq and Syria. Living on-site with the archaeological team, Christie would spend mornings typing the mystery novel that would help pay for her husband’s expedition the following year. She only gave up her yearly visit to West Asia in 1958; at 67, she finally felt too old to sleep in a tent.

Which is not to say that she settled down. Christie’s nephew recalls egging her on as a young boy to drive her new car, a Wolsey 1500, at its maximum velocity of 85 m.p.h. along the U.K.’s newly built M4 motorway.

By the time she died, in 1976, aged 85, a lot of her readers had come to confuse Agatha Christie with one of her most popular characters, the elderly Miss Marple, hanging out in an English village, twitching curtains. On the contrary, Christie was a thoroughly modern world traveler, swooping through life at speed.

Lucy Worsley, O.B.E., is chief curator at Historic Royal Palaces, and an author of history books. Her new book, Agatha Christie: An Elusive Woman, will be published on September 6 by Pegasus Crime