"Heroes of Olympus" is a five-book series written by Rick Riordan. It follows a group of demigods, the children of Greek and Roman gods, as they embark on quests to save the world from ancient threats. The story introduces new characters like Jason Grace, Piper McLean, and Leo Valdez, while also featuring familiar faces from the previous series, Percy Jackson and Annabeth Chase. The series explores themes of friendship, bravery, and identity, as the characters navigate their powers and destinies. Each book combines adventure, humor, and mythology, making it accessible for young readers and fans of fantasy literature.