Artemis Fowl wants to find his father, held hostage in Russia. Holly Short wants to find who is supplying the goblins with human technology. Foaly wants to find out who has disabled all the LEP Technology and pointed the finger at him. Meanwhile, down in the underground world, chaos has arisen. An unknown traitor has stolen forbidden weapons and armed a horde of trolls, setting them loose to wreak havoc on the citizens. Clues lead Captain Holly Short...

Demigod Percy Jackson, still with no memory, and his new friends from Camp Jupiter, Hazel and Frank, go on a quest to free Death, but their bigger task is to unite the Greek and Roman camps so that the Prophecy of Seven can be fulfilled.