This series features the heroes of Jules Verne's famous novel. During the American Civil War, a group of Union soldiers from various backgrounds manages to escape aboard a hot air balloon. Caught in a storm, the balloon is carried far from land, over the Pacific Ocean, and eventually crashes on a deserted island. Unfortunately, one of the passengers, an engineer, falls from the balloon far from the shore, and his companions believe him to be dead. But beneath the sea, mysterious figures recover the castaway and place him in a watertight container. While his companions search for his body on the beach, they are astonished to find him unharmed, but suffering from amnesia, in a small cave. The castaways soon realize that they are not alone on the island and that there is a territory forbidden to them…