Rick Riordan

When the goddess Artemis disappears while hunting a rare, ancient monster, a group of her followers joins Percy and his friends in an attempt to find and rescue her before the winter solstice, when her influence is needed to sway the Olympian Council regarding the war with the Titans.

After their father's research experiment at the British Museum unleashes the Egyptian god Set, Carter and Sadie Kane embark on a dangerous journey across the globe--a quest which brings them ever closer to the truth about their family, and their links to a secret order that has existed since the time of the pharaohs.

After learning that he is the son of a mortal woman and Poseidon, god of the sea, twelve-year-old Percy is sent to a summer camp for demigods like himself, and joins his new friends on a quest to prevent a war between the gods.

"The Greek and Roman demigods will have to cooperate in order to defeat the giants released by the Earth Mother, Gaea. Then they will have to sail together to the ancient land--Greece itself--to find the Doors of Death"--

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.

Magnus and his friends set sail for the farthest borders of Jotunheim and Niflheim in pursuit of Asgard's greatest threat, Loki's demonic ship full of zombies.

Carter Kane and his sister must prevent the chaos snake Apophis from breaking free in a few days' time or the world will come to an end. To have any chance of battling these Forces of Chaos, the Kanes must revive the sun god Ra.

Magnus Chase has always been a troubled kid. Since his mother's mysterious death, he's lived alone on the streets of Boston, surviving by his wits, keeping one step ahead of the police and the truant officers. One day, he's tracked down by an uncle he barely knows - a man his mother claimed was dangerous. Uncle Randolph tells him an impossible secret: Magnus is the son of a Norse god. The gods of Asgard are preparing for war. Trolls, giants and worse...

"The Greek and Roman demigods must simultaneously prevent the earth mother, Gaea, from waking and stop war from breaking out at Camp Half-Blood"--

The Greek god Apollo, cast down to earth as the ungifted human teenager Lester Papadopoulos, 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.