The Battle of the Labyrinth (Percy Jackson and the Olympians #4) by Rick Riordan

Teenage demi-God, Percy Jackson is back in the fourth installment of the Percy Jackson and the Olympians series. Percy continues to battle the evil forces who want to resurrect the Titans and overthrow the Olympian Gods. This time, Percy must navigate an underground labyrinth and find the workshops of its creator, Daedalus, and convince him not to help Luke use the maze to invade Camp Half-Blood. Percy and his friends are going to need all the help that they can get, and find unlikely help in the form of a mortal girl who can see through mist. The non-stop action and wit are sure to appeal to a variety of teen readers, especially middle school boys, and will no disappoint series fans. Percy is a likeable character whose loyalty and determination will speak to many readers, as will his struggles with the fairer sex. A great blend of mythology and fantasy makes this series an interesting (and educational) read. The cliff-hanger ending will have them anxiously awaiting the next installment.