Number 3 in the original Tom Swift series. Tom and the aviator he rescued from a fiery death plunge in the previous book are building a new type of airship. Part dirigible and part airplane it will use a special new gas for lift inside it's thin aluminum upper tank. And so, once complete and with Tom's friend Mr. Damon coming along, the trio set out for a trip down and up the eastern states. unknown to them Tom has been implicated in a robbery back in Shopton. As they fly unaware the authorities are after them, they encounter a terrible forest fire that nearly spells their doom, and find themselves being fired on by people they approach in the ship.

Finally, word reaches Tom about the wrongful accusation and it becomes a race to return safely to Shopton to clear his name and to find the real criminals.