Sukey's new step-pa is a mean, bossy man she calls "Mister Hard-Times." He makes her work in his garden all day and Sukey's ma doesn't seem to care. One day, when her step-pa isn't looking, Sukey takes her chance to run away to her secret hiding place by the sea.

There, she meets Mama Jo, a beautiful black mermaid. Mama Jo's got a surprise for Sukey: a magical kingdom beneath the sea without time or pain. But there are also no people. Is it really better than the world above?