Meet Isadora Moon's mermaid friend, Emerald! Emerald is learning how to be a mermaid princess, but there are just so many rules. She loves having fun with her friends and exploring her underwater world with her pet octopus, Inkibelle, she doesn't want to be stuck in the palace with everyone looking at her and checking that she's doing things the proper, royal way.

In Emerald and the Magic Shell, Emerald goes on a camping holiday with her mum, stepdad King Auster, and stepsister Delphine. But it isn't like the camping trips Emerald used to take with her dad when she was little. King Auster uses his magic shell at every opportunity to make the trip more luxurious. Emerald is determined to do camping properly, without magic, but when she wakes up in the night feeling cold, she decides to use the shell after all-to disastrous effect!