Master storyteller Alice Hoffman has written a tale of enchantment: a luminous lesson in how to say goodbye and how to hold on to those we love best of all. Hailey and Claire are spending their last summer together when they discover something at the bottom of the murky pool at the Capri Beach Club. There in the depths is a mysterious and beautiful creature with a sharp tongue and a broken heart: a mermaid named Aquamarine who has left her six sisters to search for love on land. Now, as this mythological yet very real being starts to fade in the burning August sun, a rescue is begun. On the edge of growing up, during a summer that is the hottest on record, Hailey and Claire learn that life can take an unpredictable course, that friendship is forever, and that magic can be found in the most unexpected places.
Martha Glimmer and her friends Trout and Eel decide to run away from home to find what each most desires, but their journey is cut short by a storm that brings all characters in the story face to face with their own true nature.