When demonic cheerleaders invade his high school, Percy Jackson hurries to Camp Half Blood, from whence he and his demigod friends set out on a quest through the Labyrinth, while the war between the Olympians and the evil Titan lord Kronos draws near.

While the Olympians struggle to contain the rampaging monster Typhon, Kronos begins his advance on New York City, where Mount Olympus stands virtually unguarded. Now it's up to Percy Jackson and an army of young demigods to stop the Lord of Time.

"An ultimatum has been issued: for the Survey Corps to continue the good fight of helping humanity expand beyond the Walls again, they must mount an expedition and prove that the new Vertical Maneuvering Equipment is capable of killing a Titan. But part of the preparation is to actually see the Titans and understand what humanity's greatest foe really looks like-a challenge more daunting than any written test ..."--Back cover.

Caught in the middle of an ancient power struggle, Emily and Pegasus must venture to Diamond Head volcano in Hawaii to track down the one thing that can save Olympus--before the Titans get there first.

The long-awaited prophecy surrounding Percy Jackson's sixteenth birthday unfolds as he leads an army of young demigods to stop Kronos in his advance on New York City, while the Olympians struggle to contain the rampaging monster Typhon.