A scholar and explorer, Dr. Samuel Fergusson, accompanied by his manservant Joe and his friend professional hunter Richard 'Dick' Kennedy, sets out to travel across the African continent, still not fully explored - with the help of a balloon filled with hydrogen. He has invented a mechanism that, by eliminating the need to release gas or throw ballast overboard to control his altitude, allows very long trips to be taken. This voyage is meant to link together the voyages of Sir Richard Burton an