This time, Shetland pony Choccie and his friends are supposed to go for a short vacation in their former home of Dammbüll. But as soon as they arrive, everything goes wrong: The humans get chickenpox and now the ponies are supposed to spend their time alone on a lonely island until the humans are healthy again. The island is reportedly home to a strange sea creature. And what is with all this garbage on the beach? Are ruthless environmental criminals responsible?