Several months after their adventures in Antarctica, Blake and Mortimer are back in England. Still somewhat shaken after his ordeal, the professor is ordered by his doctor to get some rest. In typical Mortimer fashion, he decides to spend his holidays in Africa... looking for a lost civilisation! Accompanied by Nastasia Wardynska and an old flame of his, he begins tracking down a culture that is older than any ever recorded—but someone is dogging their every step...