Ruby's dad has arrived home with a wonderful surprise - Coco the sausage-dog puppy! And when the family go on holiday to the seaside, of course Coco will be coming too. The beach is such an exciting place for a dog, and Ruby and Coco can't wait to spend the day splashing in the waves and playing in the sand. But disaster strikes when Coco disappears. Suddenly she's lost and all alone on the huge, busy beach ... Will she ever find her way back to Ruby?