Launched in September 2008 with Rick Riordan’s The Maze of Bones, The 39 Clues is a multimedia adventure series that includes books by a stellar roster of authors, collectible cards, and an online game that enables kids to play a role in the stories. There are 8.5 million copies of the novels in print and the concept has been licensed for publication in 24 languages. On August 31, Scholastic will release the final book, Into the Gauntlet by Margaret Peterson Haddix, with a 750,000-copy first printing and considerable fanfare. To build the buzz, the publisher kicks off its “Access Granted” 39-Day Countdown campaign tomorrow; we’ve got the details of that initiative, as well as a look at the series’ success to date.

Fast Out of the Gate

The 39 Clues follows Cahill family members’ race to be the first to assemble all 39 clues hidden around the world in order to discover what makes the clan so powerful. The characters’—and readers’—quest involves brushes with famous historical figures. Riordan, who mapped out the 10-book story arc in addition to penning the debut novel, scored a hit early on with The Maze of Bones. That title debuted at #1 on the New York Times bestseller list, as did Book 2: One False Note by Gordon Korman three months later. Subsequent titles in the series, written by Peter Lerangis, Jude Watson, Patrick Carman, Korman, and Linda Sue Park, have all appeared on bestsellerlists.

Stacy Lellos, Scholastic’s v-p of trade marketing, cites several key components of the series’ success. “One of the reasons that the program stood out is that it was conceived from the start as fully immersive,” she says. “The books, the cards, and the Web site each has an equally significant role to play, and there is nothing quite like that in the market. The scope of the Web site and the depth and richness of the online game are very ambitious for a children’s book property, and that, along with the cards and books, makes this series unique.”

Also fueling The 39 Clues’ high profile is the enthusiasm and promotional involvement of the authors. “We were fortunate to have a dream team of authors, all of whom have been great believers in the series and consistently interact with readers,” Lellos says. In addition to making bookstore, school, and library visits to promote the series, the authors have posted videos and blogs on the 39 Clues Web site as well as on various social media outlets.

Additionally, what Scholastic’s David Levithan at the series’ launch called its “subversively educational” feature (Benjamin Franklin, Mozart, and Amelia Earhart are among those making appearances) seems to have driven sales of and support for The 39 Clues. “We do believe that is why educators and librarians have embraced this series so widely,” Lellos says. “But the kids also love these books because they are fun.”

Librarians, Booksellers Rally ’Round

Among the librarians who jumped aboard The 39 Clues bandwagon early on is Rose Hagar, media specialist at Absecon Schools Media Center in Absecon, N.J. While visiting her schools the spring before the series’ launch, Gordon Korman mentioned its pending arrival and immediately sparked kids’ interest, Hagar recalls.

She subsequently booked Peter Lerangis, author of Book 3: The Sword Thief, to speak to her students. “In preparation for his visit, I organized a 39 Clues Book Club for my middle-school students,” Hagar says. “They read the first three books in the series, and we met once a week for eight weeks. We used the series’ Web site, the kids were very into collecting the cards, and I had them do a bit of research about the destinations characters go to in the novels. Some of the kids were amazed to learn that the places actually exist.” In addition to speaking to a larger group of students, Lerangis spent an hour with book club members during his visit.

Hagar went on to start a 39 Clues book club for elementary school students and organized a second club for middle schoolers, focusing on Books 4-7. A highlight of the latter was a Skype interview with Gordon Korman, in which he answered kids’ questions. “He has such a great sense of humor—he’s still a kid at heart,” she says. “The kids loved him and it was a great thrill for them.”

This year, The 39 Clues was selected as the theme of Barnes & Noble’s annual chain-wide summer reading program. Debra Gaynor, community relations manager of the B&N in Huntington, N.Y., helped organize a kick-off event there in May, which Riordan, Korman, Lerangis, and Jude Watson attended. She notes that her store had previously hosted the first three authors at individual events when their additions to the series had come out, adding, “We were very fortunate to get all four of these authors together at once. It was a fabulous event and the turnout was tremendous.”

This B&N store also displays a map highlighting the locales visited in various 39 Clues books and has just wrapped up a seven-week program, during which young readers participated in craft projects based on the international settings of the adventures. “The kids love the books’ mystery and adventure, as well as exploring different places,” says Gaynor of the series’ appeal. “They also like the gaming aspect and the cards, and all the intricacies that go with the program. And I love the fact that each book has a different author’s view, but it is all tied together so well.”

Another bookseller who is tapping into The 39 Clues’ popularity creatively is Shelly Plumb, owner of Harleysville Books in Harleysville, Pa., a suburb of Philadelphia. In August, her store will hold a five-day 39 Clues Adventure Camp for young readers entering third through fifth grades. “We’ll have activities and games imitating the adventures in the books,” says Plumb. “And we are planning on having Peter Lerangis Skype in to talk to campers.”

Praising the series for “being great adventures, having boy and girl characters that make the books non-gender specific, and integrating history into the stories,” she explains that the novels have crossover appeal between elementary and middle-school students. The series’ educational component and potential curriculum connections led Plumb to spotlight The 39 Clues in one of her store’s workshops for teachers.

The Final Adventure

Author of more than 20 books for young readers, including The Shadow Children and The Missing series, Margaret Peterson Haddix experienced a range of emotions when she was approached to write the concluding 39 Clues adventure. “I was honored to be asked, and definitely intrigued by the whole premise,” she says. “But because of the secrecy surrounding the series, there were certain things I wasn’t allowed to know until I actually agreed to write the book. So that was a bit intimidating. But, also, a bit enticing.”

Haddix admits that the prospect of tying up such a successful series was also daunting: “Everyone I ran into said, ‘Wow, you’ll have to wrap up all the loose ends that everyone else got to leave dangling. Are you sure that’s even going to be possible?’ Of course, the earlier books in the series were already beloved and kids cared about what was going to happen to the characters. So I felt a great responsibility to end everything well.”

Fans will be pleased to know that there is still more to come on The 39 Clues front. Rick Riordan’s The 39 Clues: The Black Book of Buried Secrets, a guide to 500 years of Cahill family secrets, is due from Scholastic on October 26. And movie rights to The 39 Clues have been acquired by DreamWorks Studios, with Steven Spielberg reportedly eyeing to direct. Deborah Forte, president of Scholastic Media, will produce the film and Jeff Nathanson is penning the script.

Highlights of the “Access Granted” 39-Day Countdown Campaign

• ”Access Granted” blog tour, beginning July 23 with a video post by Rick Riordan, features video and text posts from the seven 39 Clues authors that will appear on parents’ and technology Web sites.

• ”Access Granted” live global Webcast on August 31 at 4:00 ET: all seven authors will participate via live feeds, answering kids’ questions from around the world. The Webcast can be accessed for free by logging on to a dedicated Web site.

• The 39 Clues Countdown widget: starting July 23, a countdown widget clock will be distributed to various outlets online, including retailers’ Web sites, social media outlets, as well as parents’, educator and technology blog sites.

• TV advertising campaign: a 30-second commercial will air in 17 markets in the U.S. more than 6,000 times starting in mid-August, reaching more than 17 million households.

• 39-Day Countdown online advertising campaign: banner ads promoting the August 31 live online event will run on Facebook as well as other children’s Web sites, equaling more than 15 million impressions.

The 39 Clues Book 10: Into the Gauntlet by Margaret Peterson Haddix. Scholastic, $12.99 Aug. ISBN 978-0-545-06050-9