1860. Brother and sister Ballantyne travel from London to the jungles of Africa. They will face grueling hikes through waterless terrain, deadly battles with wild animals and natives, and treasure hunts in the mysterious cities of a lost ancient civilization. The heroes are constantly on the verge of death: they have to fight bloodthirsty pirates and greedy slave traders, experience the pangs of hunger and the treachery of the leaders of African tribes.