The magic ring that Emily Windsnap - half mermaid, half ordinary girl - finds buried in the sand belongs to Neptune, and he wants it back.

But the ring, once on, won't come off, and Neptune puts a terrible curse on Emily. A wildly exciting underwater adventure, written with warmth and charm, and with fascinating new characters as well as old friends like mystic Millie, creepy Mr Beeston, and Emily's mermaid friend Shona Silkfin.