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.

Caught in the middle of an ancient power struggle, Emily and Pegasus must venture to Diamond Head volcano in Hawaii to track down the one thing that can save Olympus--before the Titans get there first.

Presents a guide to the characters, settings, and mythologies of the "Percy Jackson & the Olympians" series, including descriptions of Camp Half-Blood, beasts Percy encounters in his adventures, and the gods and goddesses featured in the series.