Neptune, King of the ocean, sends half-mermaids Emily and Aaron to the land of the midnight sun to investigate the source of the dangerous storms brewing in the ocean.

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.

Emily is headed to a tropical island for a relaxing vacation with friends and family. And this time, Emily promises her best friend, Shona, there will be absolutely no adventure just plenty of fun. But somehow excitement always seems to find Emily, and before she knows it, she ends up on the other side of a powerful waterfall on a forgotten island no one else can get to.