But things don't stay quiet for long. Percy soon discovers there is trouble at Camp Half-Blood: the magical borders which protect Half-Blood Hill have been poisoned by a mysterious enemy, and the only safe haven for demigods is on the verge of being overrun by mythological monsters. To save the camp, Percy needs the help of his best friend, Grover, who has been taken prisoner by the Cyclops Polyphemus on an island somewhere in the Sea of Monsters, the dangerous waters Greek heroes have sailed for millennia-only today, the Sea of Monsters goes by a new name, the Bermuda Triangle.

Now Percy and his friends-Grover, Annabeth, and Tyson-must retrieve the Golden Fleece from the Island of the Cyclopes by the end of the summer or Camp Half-Blood will be destroyed. But first, Percy will learn a stunning new secret about his family-one that makes him question whether being claimed as Poseidon's son is an honor or simply a cruel joke.

As an incoming freshman, Percy isn't expecting his high school orientation to be any fun. But when a mysterious mortal acquaintance appears, followed by demon cheerleaders, things quickly move from bad to worse. In this fourth installment of the blockbuster series, time is running out as war between the Olympians and the evil Titan lord Kronos draws near. Even the safe haven of Camp Half Blood grows more vulnerable by the minute as Kronos's army prepares to invade its once impenetrable borders. To stop them, Percy and his demigod friends will set out on a quest through the Labyrinth-a sprawling underground world with stunning surprises at every turn. Full of humor and heart-pounding action, this fourth book promises to be their most thrilling adventure yet.

All year the half-bloods have been preparing for battle against the Titans, knowing the odds of a victory are grim. Kronos's army is stronger than ever, and with every god and half-blood he recruits, the evil Titan's power only grows. 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. In this momentous final book in the "New York Times" best-selling series, the long-awaited prophecy surrounding Percy's sixteenth birthday unfolds. And as the battle for Western civilization rages on the streets of Manhattan, Percy faces a terrifying suspicion that he may be fighting against his own fate.