Are aliens stealing things from a Japanese island and dragging them underwater? Ant believes that's perfectly reasonable. The Nektons investigate and find something even more dangerous! But can they escape?

Captain Hammerhead has captured the Nektons aboard his sub! But his rusty vessel is about to sink. The Arronax could save them all, but first, Hammerhead would have to free the Nektons and that's not exactly in his character.