After finally convincing her mother that she should take swimming lessons, twelve-year-old Emily discovers a terrible and wonderful secret about herself that opens up a whole new world.

When she incurs Neptune's wrath by finding a diamond ring buried under rocks in the ocean, Emily is put under a curse that will force her to choose to be either a mermaid or a human and split up her parents forever.

The New York Times best-selling series continues with the half-mermaid embarking on an icy and perilous journey to the Land of the Midnight Sun.Strange storms are blowing up from the ocean, caused by the nightmares of Neptune, King of the Sea. Convinced that his dreams herald an approaching threat, Neptune enlists half-mermaids Emily Windsnap and Aaron for a top-secret mission to find and eliminate the source of the trouble. But Emily and Aaron quickly...