I enjoy the entire Percy Jackson series not only because it is fast-paced and full of twists and turns but because it is a great place to start reading about mythology. When I started reading "The Lightning Thief" I decided to check out a book on Greek mythology so that I could get more background on the characters. Also, check out www.theoi. com for an awesome site that covers everything about Greek mythology. This site includes the primary sources (where the stories first came from) for all of the myths, Gods, and creatures!