In the trailer for Percy Jackson and the Lightning Thief currently debuting in front of Harry Potter, we see Percy (the modern-day son of Greek god Poseidon) taking an elevator ride up to Olympus. But all is not quite what it appears, explains Rick Riordan, who literally wrote the book on Percy Jackson:
A few people have asked, "Was that scene in the book?" No, I don't think it's supposed to be a scene from the book *or* the movie. To the best of my knowledge, it's a special scene they created exclusively for the trailer to get your attention.
He says he does like what he's seen so far, but cautions fans that they should definitely be expecting some changes.
What you'll be seeing is not the Lightning Thief book copied page for page onto the screen. What you'll be seeing is [director] Chris Columbus's interpretation of the Lightning Thief story.
The changes may be fairly substantial, as Columbus has already suggested. Yet, the real question, as Riordan sees it, is not whether it's exactly the same story, but whether it is a good story in its own right. And for an answer to that question, we'll have to wait and see.