Percy Jackson & The Olympians Vol. 03 Titans

When Percy receives an urgent distress call from Grover, he immediately prepares for battle. He knows he'll need his powerful demigod allies, Annabeth and Thalia. The demigods race to the rescue, only to find that Grover has made an important 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. Now, Percy and his friends are faced with their most dangerous challenge -  the chilling prophecy of the Titan's Curse. They must rescue the goddess Artemis by the Winter Solstice, or all will be lost including Annabeth. Available in softcover and hardcover editions.