From the introduction:
In the endless waters of the pacific there was once a mother island, Te Fiti. From her came all the bounties of life, and the world was a happy place. Then, one day, the trickster Maui stole Te Fiti‟s Heart and a slow and inexorable darkness spread across the world, bringing death and decay wherever it passed. Maui, for his temerity, was imprisoned on a deserted island.
That was a thousand years ago. Now, at last, the Ocean has chosen someone, a young girl, the daughter of the Chief of the island of Motonui, named Moana, to take the Heart back to Te Fiti. She is currently a child, but in eight years or so, she‟ll depart her island home and sail off to find Maui and convince him to guide her across the vast sea to her destiny.