When Apophis, the chaos snake, threatens to plunge the world into eternal darkness, siblings Carter and Sadie Kane plan to use an ancient spell to destroy the snake, but first must rely on the murderous ghost of a powerful magician.
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.
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.