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.

Thirteen-year-old Rory discovers a spirit world that thrives alongside his contemporary New York City, filled with fantastical creatures and people from the city's colorful past who have become gods and goddesses and who have chosen Rory to perform a dangerous mission.

As thirteen-year-old Rory continues his mission in Mannahatta, a spirit realm that co-exists alongside modern-day New York City, filled with fantastical creatures and people from the city's colorful past, he discovers that his father, whom he never wants to see again, is the only hope for peace.

"The people suffer under the centuries-long rule of the Moon Throne. The royal family--the despotic emperor and his monstrous sons, the Three Terrors--hold the countryside in their choking grip. They bleed the land and oppress the citizens with the frightful powers they inherited from the god locked under their palace. But that god cannot be contained forever. With the aid of Jun, a guard broken by his guilt-stricken past, and Keema, an outcast fighting...