It has long been a rich slice of publishing lore: just days before Paris fell to the Nazis in 1940, Hans and Margret Rey, German-born Jews, escaped from that city on bicycles, carrying with them the manuscript of what would become Curious George.

Now fans of these prolific book creators can learn the details of their remarkable flight and the events leading up to it. Due this fall from Houghton Mifflin is The Journey That Saved Curious George: The True Wartime Escape of Margret and H.A. Rey by Louise Borden, featuring watercolor art by Allan Drummond.

In her introduction, Borden explains that she had long been intrigued by the Reys' story and—curious like George—she was determined to learn more about it. Her research for the book took her on many journeys of her own. Following leads from the Reys' letters and journals, the author traveled to some of the cities and addresses that the couple had visited, contacted individuals from four countries whom the Reys had known and pored over the couple's expense records and travel documents.

Eleni Beja, an assistant editor at Clarion, worked with Borden on the book and praised the author's exhaustive investigation of her subject. "Before the contract was even signed, Louise had done 10 years of research," Beja said.

Beja was the third editor—after Amy Flynn and Emily Linsay—to work on Journey. She notes that there were many decisions to be made about the book's layout and illustrations as the project neared completion. "We debated about how to present a huge amount of information without losing the story, which is such an exciting adventure. We made a wise choice to illustrate the book in two parts, the first of which combines Allan's illustrations with archival material. The second section, which focuses on the journey, is illustrated only with art."

The tenor of the art was also a concern; in Beja's words, "How do you illustrate a book about people in time of war and still retain the humor and spirit of the Reys?" She commends Drummond for finding a way. "He did a wonderful job with that delicate balance. And his art hints at the Reys' own visual touch, yet is self-distinguished. Louise's passion for her subject is contagious—and Allan caught the bug happily."

The book's pub date is September 16, the 107th anniversary of Hans Rey's birth. Hans passed away in 1977; Margret died in 1996.