Percy Jackson and the Olympian, The Last Olympians

Percy Jackson & the Olympians is a series of fictional adventure and fantasy books authored by Rick Riordan. Set in the United States, the books are predominantly based on Greek mythology. The series consists of five books, as well as spin-off titles such as The Demigod Files and Demigods and Monsters. The Lightning Thief, the first book, is the basis of a film called Percy Jackson & the Olympians: The Lightning Thief, which was released in the United States and Canada on February 12, 2010.

The protagonist is Percy Jackson, who discovers that he is the son of Poseidon, god of the sea. He learns that the legendary beings of Greek mythology still exist and have always existed, including monsters, cyclopes, empousae, Titans, and the Greek Gods, including the twelve Olympians themselves who dwell in Olympus, which is now situated on the mythical 600th floor of the Empire State Building. Percy is frequently attacked by monsters because he is a child of one of the "Big Three": king of the gods and the god of the sky, Zeus, the god of the sea, Poseidon, and the god of the Underworld, Hades, who made a pact after World War II to not have any more children because they were too powerful and unpredictable.The other reason for the pact was a great prophecy ,predicted by the Oracle, that a child demigod of the "Big Three" would decide the fate of Olympus and the gods(good or bad)would be decided when the demigod child reached the age of sixteen.The pact was made in an effort to prevent the prophecy from ever happening: both Zeus and Poseidon break the pact by having demigod children after the war (Zeus had Thalia Grace and Poseidon had Percy Jackson). Hades however ironically (he is meant to be the most untrustworthy god) did not break the pact as he did not have any demigod children after the pact. Still he had Bianca and Nico di Angelo who were born before the war, but were trapped in the Lotus Casino for seventy years. This meant they were still able to fulfill the prophecy. Percy meets many other young demigods, both friendly and hostile, who are also in the process of discovering their ancestry and powers.