Riordan, Rick. 2008. The battle of the labyrinth. New York: Hyperion.
Although I did not read books 2 and 3, I was able to pick up the story line for the Battle of the Labyrinth easily. Of course, being book 4, the novelty of the modern day Olympian has worn off, but the series still has a loyal following. There are the usual jokes and a few plot twists. In this installment, Percy Jackson, half-blood son of the Greek god, Poseidon, embarks on a quest with his friend Annabeth into Daedalus' labyrinth. Some of the plot lines seem familiar - a master weapon being re-forged (Lord of the Rings), a dark lord being re-formed (Harry Potter series), but this just illustrates the timeless nature of the Greek myths. This is another solid entry in the Percy Jackson and the Olympians series.
The upcoming movie, "The Lightning Thief," should spur renewed interest in the entire series. Rick Riordan's website http://www.rickriordan.com/ shows that he is committed to promote reading. He knows how to connect with kids.