Tug sailing ship Garden City, bound from San Francisco to New York by way of the Horn, has for passengers Bert Livingston and his sister Lily, eon and daughter of the owner, together with their friends John and Louise Winton. Struck by a severe storm, the vessel is sent far to the south out of her oourse, and finally brings up on an ice field, after losing overboard all except the four passengers and one sailor, Tom Applegate. Although they are in no immediate danger, there seems small chance of ultimate rescue, but finally a strange air ship appears above them, a ladder is let down, and they are taken on board by the owner, who introduces himself as Baron Montavo. They are royally entertained, though they cannot but feel that there is a mystery about the whole experience—a mystery that is farther than ever from elucidation when the air ship enters a hole in the earth and begins to drop downward. After days of traveling the air ship comes to a stop and the baron conducts his guests to a palace where they are presented to the queer dwarf rulers of the land—the strange, new land in which they find themselves—the inside of the earth. In course of time they become good friends with two of the inhabitants of the Under World—the Princess Listra and Prince Ravello, and make good progress in the language. Then a revolution breaks out among the Undre, as the people of the earth's interior are called. It seems the Media are in league with the Frods, who have the Tolfs, certain monsters, half beast, half human, to help them in the war against the king and his followers. Montavo bids the Americans trust no one except Listra, Ravello, and Breeze, his dwarf man servant, and when the worst comes, to seek refuge in a tower of the palace in which they can be walled up and protected as far as may be from the Tolfa, which are what they have to fear most. The baron himself will be away in his air ship, the Meteor, in command of the fleet that is to make a determined resistance to the enemy around the tower.