With the Harry Potter series now completed, Scholastic, the United States publisher of those wildly successful books by J.K Rowling, is moving forward with what it hopes will be its follow-up blockbuster series.

Called 「The 39 Clues,」 this series will feature 10 books – the first of which is to go on sale next September – as well as related Web-based games, collectors' card and cash prize. The project demonstrates Scholastic's acknowledgment that as much as the publisher heralded the renewed interest in reading represented by the Harry Potter books, many children are now as transfixed by Internet and video games as they are by reading.

「We want to go where the kids are and really be part of their complete world, rather than going to one aspect of their world,」 said David Levithan, an executive editorial director at Scholastic. He added, 「We talk of it as being subversively educational.」

The series will be aimed at readers 8 to 12 and offer mystery novels telling the story of a centuries-old family, the Cahills, who are supposed to be the world's most powerful clan. According to the books, famous historical figures ranging from Benjamin Franklin to Mozart were members of the family. The plots will revolve around the race by two young Cahills, Amy, 14 and Dan, 11, against other branches of the family to be the first to find the 39 clues that will lead to ultimate power.

Rick Riordan, the best-selling author of Percy Jackson series, which includes 「The Lightning Thief」 and 「The Sea of Monsters,」 mythologically themed books aimed at preteens, has written the first title in this new series, 「The Maze of Bones.」 He has also outlined the story arc for the next nine installments.

The series is Scholastic's attempt to create a branded franchise for which it owns all the rights. Ms. Rowling retained the rights to the Harry Potter series, which meant that she could pursue separate deals for film and other licensed products, effectively cutting out Scholastic.

An online game will allow readers to search for the 39 clues themselves, while solving puzzles and playing minigames that will be refreshed daily. Mr. Levithan said the site would include blogs written from the points of view of characters, and maps, treasure hunts and videos.

Each book will come with six collectors' cards that can be used to find further clues in the online game. Players can also win cash and other prizes.

The publisher hopes that reluctant readers will be drawn to the books by the game. 「Reading the books will make you better at the games, so that is the incentive,」 said Suzanne Murphy, publisher of Scholastic's trade division.

Jesse Soleil, director of the Lab for Information Learning, a research group within Scholastic that has been developing new projects, said many gamers were already avid readers. But for those who aren't, he said, the series is 「about living where these kids are, and even if they are reading the books for information for the game, hopefully they will get some entertainment, and it will get them into reading.」

Mr. Riordan was drawn to the series partly because of the gaming component. 「I'm a gaming geek from way back,」 he said, recalling his passion for Dungeons and Dragons as a teenager. Now he plays online games like World of Warcraft with his two sons.

But he said he didn't try to write the first book with specific gaming outcomes in mind. 「My main certain was crafting an adventure novel that would stand on its own, even if kids never access the Internet at all,」 Mr. Riordan said.

As for whether attaching the books to an Internet game could help recruit new readers, he said: 「Some kids are always going to prefer games over books. But if you can even reach a few of those kids and give them an experience with a novel that makes them think, 『Hey, reading can be another way to have an adventure,' then that's great. Then I've done my job.」