It was a very hot summer in Donegal in 1976 - the hottest one that Emer and her friends Fedelma, Kit and Dog had ever known. And it was the summer that so many things were going to change. It all started with a dolphin swimming into Union Cove bay. At first it was fun sneaking out at night to swim with the dolphin they named Rinn. Soon the whole village knew about Rinn, but then the gang from the next village down the coast got the idea of stealing Rinn. That's when the trouble really started.