Orpheus Collar Book order (chronological)

The fourth exciting entry in Rick Riordan's best-selling Heroes of Olympus series is now a graphic novel! At the conclusion of The Mark of Athena, Annabeth and Percy tumble into a pit leading straight to the Underworld. The other five demigods have to put aside their grief and follow Percy's instructions to find the mortal side of the Doors of Death. If they can fight their way through the Gaea's forces, and Percy and Annabeth can survive the House of Hades, then the Seven will be able to seal the Doors from both sides and prevent the giants from raising Gaea. But, Leo wonders, if the Doors are sealed, how will Percy and Annabeth be able to escape? They have no choice. If the demigods don't succeed, Gaea's armies will never die. They have no time. In about a month, the Romans will march on Camp Half-Blood. The stakes are higher than ever in this adventure that dives into the depths of Tartarus.

OLD ENEMIES AWAKEN AS CAMP HALF-BLOOD'S NEW ARRIVALS PREPARE FOR WAR When Jason, Piper and Leo crash land at Camp Half-Blood, they have no idea what to expect. Apparently this is the only safe place for children of the Greek Gods - despite the monsters roaming the woods and demigods practising archery with flaming arrows and explosives. But rumours of a terrible curse - and a missing hero - are flying around camp. It seems Jason, Piper and Leo are the chosen ones to embark on a terrifying new quest, which they must complete by the winter solstice. In just four days time. Can the trio succeed on this deadly mission - and what must they sacrifice in order to survive?

Carter and Sadie Kane's dad is a brilliant Egyptologist with a secret plan that goes horribly wrong. An explosion shatters the ancient Rosetta stone and unleashes Set, the evil god of chaos. Set imprisons Dr Kane in a golden coffin and Carter and Sadie must run for their lives. To save their dad, they embark on a terrifying quest from Cairo to Paris to the American South-west and discover the truth about their family's connection to the House of Life.

After their mother's death, siblings Sadie and Carter have drifted apart. Sadie has been living with their grandparents in London, while Carter has been traveling the world with their father, the renowned Egyptologist Dr. Julius Kane.