Greek and Roman demigods from the Prophecy of Seven must work together to seal the Doors of Death--and help Percy and Annabeth escape the Underworld in the process.

Greek and Roman demigods Nico, Jason, Reyna, Leo, and Piper try to stop Gaea, the Earth Mother, who needs the blood of two demigods sacrificed in Athens--the blood of Olympus--to awaken. Meanwhile, the friends keep having frightening visions of a great war at Camp Half-Blood that could be the end of all of them.

Will the Greek god Apollo, cast down to Earth in the pathetic mortal form of a teenager named Lester Papadopoulos, finally regain his place on Mount Olympus? Lester's demigod friends at Camp Jupiter just helped him survive attacks from bloodthirsty ghouls, an evil Roman king and his army of the undead, and the lethal emperors Caligula and Commodus. Now the former god and his demigod master Meg must follow a prophecy uncovered by Ella the harpy. Lester's...

Leaving the safety of the demigod training ground, a disgraced Apollo embarks on a quest across North America to find a dangerous ancient-world Oracle while navigating the challenges of the evil Triumvirate.

The Greek god Apollo is still in the persona of ungifted human teenager Lester Papadopoulos. Now Lester and his demigod friends must go through the Labyrinth to find the third emperor-- and an Oracle who speaks in word puzzles-- somewhere in the American Southwest. But the longer he stays mortal, the weaker he grows... and the less confident that he will be able to regain his place on Mount Olympus.

Cast down from Olympus and transformed into a human after angering Zeus, a weak and disoriented Apollo arrives in New York City as a regular teen and is forced to survive in the modern world while endeavoring to regain Zeus' favor.

Percy Jackson's hope for a normal senior year is shattered as the gods present him with three quests, beginning with the retrieval of Zeus's goblet, in order to get the necessary three letters of recommendation for college.