Percy Jackson: Good movie, bad adaptation By Carmela Verderame, 10“Percy Jackson & the Olympians: The Lightning Thief” is based on the book (2005) by Rick Riordan. This is the first book of the series. The movie and the book, however, have quite a few differences. Whole sections of the book are omitted from the movie. While some aren’t that important, one major plot point — how Percy learns he is a demigod — makes the story make a lot less sense. If you are a fan of the book, you will notice a lot of other differences, too.