Attention, Alex Rider fans: The end is near.

Author Anthony Horowitz, creator of the teenage-spy sensation, says he plans to write just two more Alex Rider books, for a total of 10 in the best-selling series. And only one of those -- the ninth, or next one -- will truly feature Alex; the 10th book will include only a minor role for the spy, and instead focus on another character, assassin Yassen Gregorovich, who trained with Alex's father.

"The 10th book finishes where 'Stormbreaker' (the first book in the series) starts, so the series will finish on a high note," said Horowitz during a recent interview at a Washington bookstore.

Why end the series, which has sold more than 10 million copies worldwide in 28 languages?

"I really do live in fear of writing a book that disappoints a kid," Horowitz said. "So the answer is just to stop."

Meanwhile, fans can happily delve into the newest, just-published Alex Rider adventure, a typically rip-roaring tale titled "Crocodile Tears" (Philomel, $17.99).

In this eighth book in the series, Alex reluctantly returns to work for MI6, the British Intelligence agency, after a journalist threatens to break his cover and make him an instant worldwide star -- something that the very private teen just can't stomach. In exchange for having British Intelligence persuade the journalist to keep silent, Alex is required to complete a "very simple" spy mission during a school trip to a research center where genetically engineered crops are grown.

Of course, nothing is simple when it involves Alex Rider, and the mission evolves into a terrifying cat-and-mouse game with the Rev. Desmond McCain. Founder of an organization called First Aid, McCain secretly works to create catastrophes where his charity can swoop in, give some help -- and then also pocket some of the millions contributed by unsuspecting donors.

As usual, Alex must use his wits to keep himself alive in "Crocodile Tears," as he comes near death numerous times. But what makes this latest adventure a bit different from previous books in the series is the fact that Horowitz has chosen to spend more of the book showing Alex's everyday, non-spy life. The result is a more rounded, complex picture of Alex, which adds further to the book's appeal.

"I wanted to ground him a bit more," Horowitz said. "I wanted to show him as an ordinary kid going to an ordinary school."

Even the spy gadgets given to Alex for his mission in "Crocodile Tears" are school-related: an eraser with a flash drive hidden inside, a "library" that opens secure doors and a calculator that jams transmissions.

Alex is 14 when the series begins, and Horowitz will end the series when Alex turns 15. It turns out that 14 is something of a magic number for Horowitz.

"I've always been interested in that window of time," he said. "You're too young to be an adult, and too old to be a kid. ... It's a time of infinite possibilities."

In "Crocodile Tears," however, it's clear that Alex is growing older. His bike is suddenly too small, for example, and his spymaster, Alan Blunt, complains that Alex is getting too tall.

"In his head, Alex is already 15. He's moving on," Horowitz said.

And so is Horowitz. In addition to wrapping up the Alex Rider series, Horowitz is getting ready to write the final volume in each of his two other children's series, "Gatekeepers" and "The Diamond Brothers." Horowitz figures it will take him about five years to complete all three series, and then he's planning to quit writing for children.

"I'm going to quit while I'm ahead," he said.

But Horowitz adds that he will continue writing for adults, including screenplays and TV series such as "Foyle's War."

With the popularity of the Alex Rider series among both boys and girls, Horowitz has gained a reputation as a writer who can persuade reluctant readers to try books. It's a reputation that pleases him immensely.

"At the same time, I know that my books are not masterpieces. I know that I'm writing to entertain," Horowitz said. "My books are the foothills -- there are mountains out there."

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