Barnacle's daughter had mysteriously disappeared one night. He doesn't want the same to happen to his son, thus keeping him confined within the walls of the Octopod. But there is more going on that the vanishing of his daughter. Kwazii seems to be hiding something from him, Shellington and Dashi's second daughter has been acting strangely ever since she turned 12. It doesn't help when his son was swept away in a storm while sneaking out for a midnight swim. (First of an ongoing trilogy of the future generation of the Octonauts)