The big day has finally arrived! It's Shyanna's thirteenth birthday, the most important birthday in a mermaid's life.
Shyanna will get her legs and be able to go on land for the first time ever!
But her excitement quickly fades when Cora's sister, Jewel, gets stuck in a fisherman's net.
Will Jewel be saved? And if so, at what cost to the other mermaids?