Although they grew up in what they described as more of a “creative adjacent” than an overtly creative household, Ann and Ben Brashares both found their way to writing. Ann, the oldest of four and the only girl, the bestselling author of the Sisterhood of the Traveling Pants series (Delacorte), was the trailblazer. While Ben experimented with the interests and careers of the other Brashares siblings (music and wildlife ecology), he eventually followed in his older sister’s footsteps.

In addition to The Sisterhood of the Traveling Pants and several other YA books, Ann is the author of adult novels including My Name Is Memory and The Last Summer of You and Me (both published by Riverhead). Ben is the author of picture books Being Edie Is Hard Today and The Great Whipplethorp Bug Collection (both from Little, Brown). For their first co-written collaboration, they met in the middle with Westfallen, a middle-grade series debuting this fall. The cover for the first in the series is revealed here for the first time.

In this time-travel mystery-thriller, present-day neighbors and former best friends Henry, Frances, and Lukas are on the cusp of many changes. They’re in middle school now and have little in common anymore aside from their past. But when they are thrown back together again, circumstances lead to the discovery of a buried radio in Henry’s backyard. It was put there nearly 80 years ago by another group of neighborhood kids, then living through World War II. After all that time underground, the radio still works, but not the way it was intended. It allows the two groups of kids to communicate with each other across time.

The present-day kids have watched enough sci-fi films to be wary of the dangers of crossing time streams: something that they do or say now might affect the outcome of events in the past. Still, they want to answer the questions of their 1940s counterparts, who are eager to learn the outcome of the war and the fates of their family members. The contemporary kids tiptoe carefully, trying to avoid giving too much away. But something goes wrong, because when they wake up on the morning of May 6, 2024, America is ruled by Nazis, and they are going to have to find a way to change it back.

Complementary Strengths

The siblings have long wanted to collaborate on a book, and despite the fact that Ann has written for teens and adults and Ben for younger readers, Ann said she always knew it would be middle grade. “I love this age group—writing for and about them. It’s also a great time of life for reading.” Both siblings currently have middle-grade children.

They brainstormed for a time, coming up with several storylines that didn’t take flight. When Ben hit on the idea of a buried radio, “That was the spark,” Ann said. “Good ideas keep opening up. They’re expansive. This one had that feeling for me.” Still, she continued, “Time travel is hard. We worked on it a long time before we figured it out.”

The idea of alternative history isn’t new, said Ben, and he knows that for adults, at least, the idea draws comparison to Philip K. Dick’s The Man in the High Castle. But the fun and interesting part of the concept was having kids from two different eras communicating, figuring out how they’d relate to each other and how they’d guide each other through mysteries and finding clues. “It’s like a logic puzzle,” he said, noting that logic was Ann’s favorite subject in college. “We spent hours going back and forth with the cause-and-effect parts and it was so fun,” she said.

Rather than juggling six different points of view (three in each time period), they chose to focus on the perspective of one character in each era, with Ann concentrating mostly on the 1940s material and Ben handling the contemporary storyline. That allowed them to work independently on parts of the book while still collaborating.

Describing their “creative give and take,” Ben said, “My favorite part of the process is when Ann says, ‘What if... ?’ She has so much experience and has had so much success with her books. She’s comfortable with plotting and structure, so I defer to her on most issues. She knows her stuff.”

Ann said the siblings have complementary strengths. “Ben has so much humor and a lot of natural flair. He’s so good at dialogue.” She likens her role to that of a jeweler placing the gems in a setting or stringing pearls together. “I love the craft of storytelling—creating hierarchy and story structure.” The two also have different work styles, she said: “I go forward. Ben goes sideways.” Creating a story through both methods resulted in a better story, she continued. “I’m grateful to Ben for slowing it down, rethinking, and redoing. It makes things better and I’m grateful for this experience.”

The siblings worked on the first book in bursts, mostly during the summer, for around three years. While there were times when they thought of letting it go, the story had taken on a life of its own and they outlined an arc over three books. Westfallen was signed as a trilogy, but the “the premise lends itself” to further exploration, Ann said. The authors hope that both the fast-paced storyline and the relatable characters will keep readers enthralled, describing the tone of the book as “fantastical, but grounded,” with a lot of humor. The subsequent books in the series are expected annually over the next two years.

The cover was designed by Chloe Foglia, with art by Leo Nickolls. Foglia said that the flame in front of the propaganda poster serves almost as “a window into another reality.” The idea was brought to life by Nicholls, she said, who added “the danger and immediacy of a lit match,” and the allusion to “communicating through time, the friendships, these young kids fighting against the threatening ominous Nazi forces, the alternate reality.” The Brashares suggested a final touch—the butterfly—“to represent the impact we have on the world,” she added: “one very small thing, like the flap of a butterfly’s wing, can have a profound effect on the future.”

Westfallen by Ann Brashares and Ben Brashares. Simon & Schuster $18.99 Sept. 17 ISBN 978-1-66595-081-7