Published originally in 1894, The Red Sultan is an adventure story about a young Scotsman, freshly graduated from university as a doctor, who runs into an old family acquaintance and learns that his grandfather, long presumed dead, may still be alive in Africa.  Since the grandfather holds the key to his own investiture as the rightful heir to the family estates, the young man, both for his own sake and his mother's, decides to head for Africa to look for him.

The author's vivid and detailed descriptions of 18th-century North Africa (when the story takes place), both cultural and geographical, are worth the read all by themselves.  Clearly, the author had firsthand experience with the Dark Continent and the modern day reader will be struck by how little has changed in more than two centuries.