Best-selling author Rick Riordan, who taught Greek mythology for many years in middle school in California and Texas, utilized ancient myths when writing the popular “Percy Jackson” series.

He had been reading the sagas of the ancient Greek heroes as bedtime stories to his son, Haley, when he thought of the series.

“When I ran out of myths, my son became disappointed,” the author relates on his website. “He asked me if I could make up some new stories with the same characters. I remembered a creative writing project I used to do with my sixth graders, which allowed them to create their own demigod hero, the son or daughter of any god they wanted, while having them describe a Greek-style quest for that hero.

“Off the top of my head, I made up Percy Jackson and told Haley all about his quest to recover Zeus’ lightning bolt in modern-day America. It took about three nights to tell the whole story and, when I was done, Haley told me I should write it out as a book.”

Riordan (pronounced Rye’-er-dan)  had already been an established author, having written several  novels (such as the Tres Navarre private-eye thriller, “Big Red Tequila,” in 1997).

“I picked a few of my sixth, seventh and eighth-graders and asked them if they’d be willing to ‘test-drive’ the novel,” Riordan says. “I’m used to showing my work to adults and had no idea if kids would like Percy. I finally understood what it must be like for them, turning in an essay to me and waiting to get their grades back! Fortunately, the kids really liked it. They had some good suggestions, too.”

Latest adaptation

The book was published in 2005, but it would be another five years before Hollywood would bring the first of the “Percy Jackson” stories to the screen. While the studio explored the idea of turning Riordan’s first book into a movie, the author continued the series by penning a new novel each year between 2006 and 2009.

Little did Riordan realize that the big-screen version of his first novel, “Percy Jackson & the Olympians: The Lightning Thief,” would become a global box-office and home-entertainment hit.

At the tail of the first “Percy Jackson” hit comes the latest movie adaptation, “Percy Jackson: Sea of Monsters,” directed by Thor Freudenthal, with the returning cast led by Logan Lerman along with Alexandra Daddario, Brandon T. Jackson and Jake Abel.

In “Percy Jackson: Sea of Monsters,” Percy isn’t feeling very heroic.  The half-human son of Poseidon—the Greek god of the sea—once saved the world, but Percy’s starting to think that might have been a fluke. Is he a flash in the pan… a one-quest wonder?

When Percy learns he has a half-brother who’s a monster, he wonders if being the son of Poseidon might be more of a curse than a blessing. But Percy doesn’t have much time to brood; the magical borders of Camp Half-Blood are beginning to fall and a horde of mythical monsters threatens to destroy the sanctuary for the children of the gods.

To save the demigods’ haven, Percy and his friends must find the fabled and magical Golden Fleece. Their journey takes them to Washington, DC, and on to the Florida coast, where they set sail on a treacherous odyssey into the uncharted, deadly waters of the Sea of Monsters, known to humans as the Bermuda Triangle.

They are challenged by a giant mechanical fire-breathing bull, terrifying sea creatures, a gigantic Cyclops, and other demigods of uncertain allegiances. The stakes are higher than ever, and if Percy doesn’t succeed, Camp Half-Blood will cease to exist and all of Olympus will crumble.

Screenwriter Marc Guggenheim and Freudenthal remained true to the spirit of the book, while making necessary adjustments in translating it for the big screen.

“There were some things that had to change [in adapting the book] because the structure of a book is very different than the structure of a movie,” Guggenheim explains. “But we always drew inspiration from the book.”

One of the biggest challenges in the adaptation, says Guggenheim, is that “the tones of the novel are very specific, and, once you put them up on a movie screen, there’s a danger that they’ll feel incongruous with each other: The seriousness of the threat of [the über-villainous] Kronos might feel at odds with the wild and zany aspects of some of the other characters. The challenge is making sure that those tones complement rather than clash with one another. Our director, Thor, always had a very clear vision for how every piece of the movie should fit together.”

“Percy Jackson: Sea of Monsters” opens Aug. 7 in theaters nationwide from 20th Century Fox to be distributed by Warner Bros.