The Titan's Curse (Percy Jackson and the Olympians, #3)

When Percy Jackson recieves an urgent distress call from his best friend Grover he immediately prepares for battle. He knows he'll need his powerful demigod allies, Annabeth and Thalia at his side; his trusty bronze sword, Riptide and...a ride from his mom.
The demigods race to the rescue to find that Grover has made an iimportant discovery; two new powerful half-bloods whose parentage is unknown. But that's not all that awaits them. The Titan lord Kronos, has set up his most devious trap yet and the young heroes have just fallen prey.
Hilarious and action-packed this third adventure in the series finds Percy faced with his most dangerous challenge so far; the chilling prophecy of the Titan's Curse.