Grace lives an ordinary life with her father and sisters by the beach. She likes nothing better than swimming and dreaming. But on her 15th birthday something extraordinary happens and Grace is transformed into a mermaid!
Assisted by Serina, a feisty dugong, Grace tries to find her way back to her own world. On the way she meets the handsome Prince Christian, some beautiful but vain mermaids and the wicked Sea Witch and her tricky lionfish. It seems as though only the Sea Witch can help Grace return to her family- but can the new “little mermaid” really trust her? And what will the witch want in return?