I've been an unabashed fan of the "Percy Jackson and the Olympians" series by Rick Riordan from early on. But one thing bugs me as I consider "The Last Olympian" (Disney/Hyperion: $17.99, ages 10 and up), the fifth and final book in the series: I am flummoxed by my inability to keep straight the plots of the five books (hereafter called "PJO").

The general premise of the series is that the Greek gods are alive and well and operating in today's world, just as they did in classical times. The plot involves a bid by the Titans, who were defeated in days of yore by the Olympian gods, to take back power. As in Greek mythology, there are demigods -- the sons and daughters of a god and a mortal -- who are the heroes (or the fools) in the constantly shifting battleground (sometimes playground) of the gods. It's the forces of order and the forces of chaos, ardor, jealousy and betrayal -- everything you adore about Greek mythology -- translated into the modern world. Mount Olympus has migrated to the top of the Empire State Building; the entrance to Hades lies under a recording studio in Los Angeles. What's not to love?

So how is it possible that the details of a story that has given me so much pleasure can have stuck with me so little?

Normally I'm a stickler for details, and my firm grasp of details is usually put to shame by my fellow readers under the age of 13. With the " Harry Potter" series, for example, I've been amazed at the details kids consider important enough to remember. The dark magic knickknacks cleared out of the cabinet in the Black family mansion? The exact tactics used in each of the take-no-prisoners Hogwarts Quidditch matches? Please! Why would I remember these things? Kids do, though.

But ask me when a character learned a piece of information that paved the way for a later plot twist and I can often pinpoint the scene. I admire how writers fit books together like jigsaw puzzles.

With "PJO," however, I found I just couldn't summarize the story. I tried diagraming the plot while I reread the books, but there was always a significant point I had neglected to note, and I was forever flipping back and trying to remember which volume it was in. It doesn't help that many clues come in the form of dreams and prophecies, which are by nature obscure in their meaning and intent, until fate has taken its course.

As research for this story, I decided to find out if kids remembered how the story hangs together over five books better than I did.

Let me admit something first: I broke the rules. I wasn't supposed to show the book to anyone before publication, because of the firm May 5 embargo. But I needed field research! I'd had the manuscript for several weeks, which was plenty of time to give in to the temptation to let several kids read it. To be honest, these kids had been bugging me for months about when the new "PJO" was coming out. To protect these brave readers against thugs hired by publishers to suppress embargo-breakage, I haven't used anyone's name.

The kids inhaled "The Last Olympian," and sometimes getting the manuscript back to me within 24 hours. And they all had the very same happy comments: It's a great final battle, and Riordan leaves open the door for more books in the series. The author once hinted that he may take up the series from another character's point of view, and here, on the final pages of the last "Percy Jackson" book, is evidence that he's thinking about it. (Now you have to imagine hordes of kids, coast to coast, punching their fists in the air and chanting: "Do It!! Do It!!")

But here was my secret reason for slipping the manuscript early to unauthorized readers: Imagine my relief to discover that they didn't remember much about the details either.

"What I like about the last book is that all the little pieces come together," said one kid.

"Like what pieces?" I asked, hoping for an angle for my review.

"Well, you finally find out what Luke's story is," she said.

"And what is Luke's story?" I asked.

"Well, his mom. . . . " I don't want to give away any plot twists, but trust me, this kid's explanation wouldn't give anything away. We do, indeed, learn Luke's story, but I'll be switched if I could tell you the details. It's a rip-roaring read, though.

And then it hit me. I absolutely adored Greek myths in childhood. But who ever remembers how all those darn gods are related to each other, or what exact stories they figure in? The important thing is to know the main ones: Zeus, Athena, Apollo, Hades, in short, the 12 Olympians, whose thrones stand in the great hall on Olympus. By the way, can you name all 12? Hades isn't one of them, and I guarantee most of you will forget either Demeter or Hestia. Moreover, there was, it turns out, "a great deal of fluidity when it came to who was counted among their number in antiquity," says Wikipedia in its article on the "Dodekatheon," the 12 Olympians. Hah! No wonder it's hard to remember.

I was comforted by a comment in my beloved "Genealogy of Greek Mythology" (Gotham Books: $25), a lovely accordion-folded book by Vanessa James which lists main characters in larger typeface to distinguish them from the fuzzier minor characters: "Ancient Greek and Latin authors often disagree about the ancestral histories of mythological characters. . . . In some cases, where multiple genealogies exist for one person, my choices about their inclusion and placement in the chart could reasonably be debated." In other words, confusion reigns.

The point is that beyond the main framework of the myths, the details are pretty much up to the individual storyteller. Homer didn't even bother to explain at the start of "The Iliad" why the Greeks were coming to sack Troy. He assumed that, whether or not his listeners remembered the details about Helen, Paris and the golden apples, they knew the war was generally a blood feud engineered by the gods and fatally compromising a host of great mortals, so he jump-started the story with an exciting storyteller's trick, and opened with a quarrel between two heroes.

And this is the secret of the infinite flexibility of mythology: The stories are there, somehow, in our genes, ready to spring to life as we listen to a new version. There have been myriad novels reworking Greek myths as psychological tales, as morality plays, as feminist stories, you name it. The better the storyteller, the better the experience.

When I interviewed Riordan in 2007, I asked him if fifth-graders know enough of the details of Greek mythology to follow the "Percy Jackson" books. Absolutely, he replied. If they haven't actually had the stories read to them, they've seen the Disney movie "Hercules," or they've seen Zeus with a lightning bolt in commercials, or they've run across the gods and heroes in some form, somewhere. They know enough to understand that when Apollo turns up driving a Lamborghini, it's totally in character. That's his chariot!

The brilliant thing that Rick Riordan has done with these books is to make true what his story says: The Greek gods have moved to wherever their stories are told. Mount Olympus can as truly be at the top of the Empire State Building as it can be on a mountaintop in Greece. The important things to know are that the gods are not all-powerful, nor are they eternal, but that the stories of heroes are eternally told.

Sonja Bolle's "Word Play" column appears monthly at