Emily Windsnap doesn't know how to swim. Her mother has always cautioned her to stay out of the water. But it's hard to make friends at the beach when everyone else is having fun in the waves. So when swimming lessons start at school, Emily is excited to finally have the chance to learn. Standing beside the pool, she feels the water calling her, but when she jumps in, she gets a strange, kind of scary sensation--like her legs are stuck together. Eager to figure out what's happening, Emily later dives into the sea. She gets that weird feeling again, but this time she looks down to see that her legs are gone--replaced by a shiny, beautiful tail.