When Kit and Nita come to the aid of a wounded whale, they are drawn into depths of wizardry beyond their wildest imaginings. The whale reveals herself as a wizard, enlisting them in a perilous battle against the sinister Lone Power.

Transformed into whales themselves, they join an ancient ritual beneath the waves, alongside whales, dolphins, and a single fearsome shark. But as they dive deeper into this magical realm, a haunting question surfaces: which poses the greater danger—the ominous Lone Power, or ed'Rashtekaresket, the enormous shark as old as the sea itself?

The ocean holds secrets and threats at every turn. Will Kit and Nita navigate these treacherous waters and emerge victorious, or will the depths claim them forever?