Alfred takes his homemade submarine into the Southern Ocean to thwart the actions of the Japanese whalers. In Australia, he is mistakenly accused of sabotaging an oil tanker, forcing him to escape to Tasmania. There he meets up with Merwin Hughes, an eccentric environmentalist, and together they travel south. They are followed along the way by a friendly blue whale and her calf, and a bond is established. Soon after, they encounter a tanker on its way to illegally refuel the whalers' ships ...