Percy Jackson is a myth. He and his friends are nothing but a story told to the new campers. Camp Half-Blood's story is still being written.

Unexplained disasters have the gods of Mount Olympus pointing fingers and passing blame while, under everyone's noses, a new era is emerging. Gaia, mother to the Titans - known to mortals as Mother Earth - has been but an observer all these years while her grandchildren hold the thrones. But as of late, the destruction of her earth has angered her. Mortals spill their own blood and poison the soils and waters. Forests are felled for man's selfish desires, and animals are forced from their homes and perish. Gaia no longer believes her grandchildren fit to watch over her world, and is ready to reclaim what is rightfully hers.

She is building an army. Gods and demigods alike join her with promises of revenge and power backing their loyalty. As the gods continue to fight, Gaia's army rises, and so do the tides; and the world awaits its saviour... or its demise.