In a foggy archipelago called the City of Islands, twelve-year-old Mara has always been fascinated by the magic that drifts on the air as songs. But when her guardian, a bone-mage named Bindy, is killed by a rival, Mara loses both her home and her best chance to follow her dream of learning magic. Now Mara is a servant for the powerful Lady of the Tides, earning her keep by diving in the murky ocean and searching for magical treasures.