Peggy the pug is going on holiday to the seaside! Her special friend Chloe is excited, too, and hopes that she'll see a mermaid. But even though Chloe and Peggy search the beach, they can't find a mermaid anywhere. Not wanting her friend to be disappointed, Peggy decides that she'll just have to become a mermaid herself! But that means that she's going to have to learn how to doggy paddle.