Robur the Conqueror

In Philadelphia (USA) a club of amateur aircraftmen meets and discusses the construction of a steerable airship, when suddenly a stranger named Robur appears and claims to already own such an airship. Since the members don't believe Robur, it comes to an argument and he disappears.
Later the president of the association together with his secretary and his servant is kidnapped by Robur and forced on an involuntary, but adventurous journey, always trying to escape their kidnapper...