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 and
John Hanning Speke in East Africa with those of
Heinrich Barth in the regions of the
Sahara and
Chad. The trip begins in
Zanzibar on the east coast, and passes across
Lake Victoria,
Lake Chad,
Agadez,
Timbuktu,
Djenné and
Ségou to
St Louis in modern-day
Senegal on the west coast. The book describes the unknown interior of Africa near modern-day
Central African Republic as a desert, when it is actually
savanna. A good deal of the initial exploration is focused on finding the source of the Nile, an event that occurs in chapter 18 (out of 43). The second leg is to link up the other explorers. There are numerous scenes of adventure, composed of either a conflict with natives or conflict with the environment. Some examples include: • Rescuing a missionary from a tribe that was preparing to sacrifice him. • Running out of water while stranded without a wind over the Sahara. • An attack on the balloon by bearded vultures, leading to dramatic developments as Joe leaps out of the balloon. • The actions taken to rescue Joe later. • Narrowly escaping the remnants of a militant army as the balloon dwindles to nothingness with the loss of hydrogen. • The shooting of a
bluebuck, now known to be anachronistic since the species was already extinct. In all these adventures, the protagonists overcome the challenges they face through continued perseverance more than anything else. The novel is filled with coincidental moments where trouble is avoided because wind catches up at just the right time, or the characters look in just the right direction. There are frequent references to a higher power watching out for them. The balloon itself ultimately gives out before the end, but makes it far enough across to get the protagonists to friendly lands, and eventually back to England, therefore succeeding in the expedition. The story abruptly ends after the African trip, with only a brief synopsis of what follows. == Film adaptations ==