Spy School is once again in session, and fans of the popular action-adventure series are rejoicing. Author Stuart Gibbs first introduced clumsy-but-brainy 12-year-old Ben Ripley in 2012’s Spy School (S&S), which launched with a first printing of 15,000 copies. In that first title, Ben is recruited to what appears to be a Virginia boarding school focused on science but is really a front for the C.I.A.’s Academy of Espionage. Now, Ben is a 13-year-old spy-in-training as he stars in the sixth volume in the series, Spy School Goes South, released October 2 with an initial print run of 85,000 copies. To date, more than 1.6 million Spy School books, in all formats, have been sold and they have been translated into 12 languages.

So far, October has brought a whirlwind of attention for the series. On October 4, Deadline Hollywood announced that 20th Century Fox has optioned the series for film, with Gibbs attached to write the screenplay based on the first book. Barnes & Noble released a simultaneous collector’s edition of Spy School Goes South on October 2, containing 16 pages of bonus material by the author and featuring a jacket with pink foil accents and a map/poster on the reverse side. (This marks the eighth time that the retailer has produced a special edition of one of Gibbs’s books). While Gibbs was on a two-week national tour supporting Spy School Goes South at the beginning of the month, the title landed on the #6 slot on the New York Times children’s series bestseller list. And the Spy School Top Secret Collection, a five-volume boxed set of paperbacks, was released on October 16.

The idea for Spy School is one that came to Gibbs quite early on. “To be honest, I came up with it in probably fourth or fifth grade when I saw my first James Bond movie,” he said. “I always liked writing stories so I wrote a Jimmy Bond story about James Bond’s son, calling it “The Kid with the Golden Water Pistol” and Jimmy was agent Double 0 6 1/2.” The Spy School idea grew from there, Gibbs noted. “I figured that James was traveling the world a lot and was not around to teach Jimmy everything he knew, so Jimmy might have gone to a top secret spy school to learn how to be a spy.”

That kernel of an idea percolated for a long while as Gibbs tried various ways to bring it to life. “When I worked as a screenwriter I tried to sell it as a movie and I tried to set it up as a TV show,” he recalled. His luck changed when he began writing middle grade novels. “After I did Belly Up [first in the FunJungle series] for Simon & Schuster, they asked if I had any other ideas and I said yes, one that I’ve been trying to do forever. That turned out to be the perfect place for it.”

According to Gibbs, the Spy School books are a bit of a reaction to the plethora of spy movies that kids have access to these days. “I think the point of Spy School is to imagine yourself in that spy world and then recognize it wouldn’t go nearly as well for you,” he said. “What I like about this world is that I can drop an intelligent character into a situation that no one could possibly be expected to handle, and it’s funny, but it’s also relatable. I’d like to think my readers are relating to Ben—and the other characters as well—as if he’s a proxy for them.”

Heather Hebert, manager of Children’s Book World in Haverford, Pa., has hosted Gibbs at her store a number of times and agrees with Gibbs’s assessment of the series’ draw for young readers. “As much as kids like crazy over-the-top fantasy, they also love the relatability of the characters—like maybe it actually could be them. Stuart has a real knack for writing a book that’s just a sliver over the reality, close enough that kids could imagine being there, but far enough removed that it keeps them turning pages.”

The look of the Spy School books is part of their appeal, too, Gibbs noted. “I have to give props to Lucy Cummins, who does the covers,” he said. “Every cover is a brilliant encapsulation of the story, as well as funny and eye-catching. They grab people’s attention. I think that iconic spy guy image she created resonates and is amazing marketing.”

Gibbs’s editor, Liz Kossnar, said that the series offers “a trifecta of fun: slapstick hilarity, enthralling mysteries, and an unlikely hero you want to see win—not to mention the arsenal of knowledge you learn, all disguised as key clues to bring the bad guys down. It’s been such an honor to work on this series and help bring these books to more and more kids.”

As a small sampling of those kids, siblings Maddie (age 15) and Cole (age 13) Stewart of Evans, Ga., weighed in with their take on Spy School. “I like that there are lots of different books in the series, all with unique styles,” said Maddie. “I never saw the ending coming—they were always surprising, and never boring. With a lot of other series, the books start to be formulaic.” Cole had a similar critique. “I like that they are mystery books where you couldn’t figure out the ending until the very end, and they portray kids in adult situations,” he said, adding, “The books always kept my interest and attention.”

Book sales and the crowds at Gibbs’s appearances have grown steadily over the past decade, but he said it’s an experience that never gets old. “I’ve been blown away by the response of kids to the books,” he said. During his just-wrapped tour, Gibbs recounted that one family had driven five hours to see him. “I really can’t say how flattering that is,” he said. “Not just that the kids want to come, but that the parents will actually drive them.” He had a similar experience in Massachusetts. “I did an event at An Unlikely Story in Pleasantville two weeks ago and they had overflow capacity and it was the night of a Red Sox game,” he said with bemusement. “Every time you see a crowd it’s unbelievable. When you’re writing middle grade, you know that kids can’t show up without their parents’ help. So it takes a whole family deciding that they’re going to show up on a school night. And that means a lot.”

Even though he’s off the road at the moment, Gibbs is still moving full speed ahead—into his future projects. “Next year, I have three books coming out,” he said, “which is the only time I’m ever going to do that.” First up is Lion Down (S&S, Feb. 2019), the next book in the FunJungle series, followed by Spy School British Invasion (S&S, May 2019), the seventh entry in that series. And he also offered a bit of news. “I’m starting a new series which I’m still waiting for my publisher to announce,” he added. “I’ve started writing the first one. It’s a middle grade action-adventure that will come out around this time next year.”

Beyond that, he’s begun work on the sixth FunJungle title and said, “I just met with an executive at Fox and they are eager to see the script, so I have to get going on that.” With a pace like that he may just need to go undercover for a while.

Spy School Goes South (Spy School #6) by Stuart Gibbs. Simon & Schuster, $17.99 Oct. ISBN 978-1-4814-7785-7