Inimitable robot Roz has made an unlikely home for herself on an idyllic island dense with forests, wildflowers and friendly animal inhabitants - including her own young son Brightbill the gosling. Life on the island is perfect, until a dying seal washes ashore and warns of dangerous, cloudy waters that are flowing toward the island, bringing new dangers for the animals. Forced inland they will have to fight over fewer resources - and Roz realises that she must march into the waves and undertake an incredible undersea journey to find a way to protect her beloved island and all who live on it.