"The Heroes of Olympus" is a five-book series written by Rick Riordan. It follows a group of demigods, including Percy Jackson and Annabeth Chase, as they embark on quests to save the world from ancient threats. The story combines elements of Greek and Roman mythology, introducing new characters like Jason Grace and Piper McLean. The series begins with "The Lost Hero" and concludes with "The Blood of Olympus." Each book features a mix of adventure, friendship, and self-discovery, as the heroes face challenges from mythological creatures and gods. The narrative emphasizes themes of loyalty and bravery.