Prester John, by John Buchan

“Prester John” tells the tale of John Laputa, a celebrated Zulu minister who has taken the title of the mythical priest-king Prester John.
South Africa, 1900. After his father dies, nineteen-year-old David Crawfurd is sent off to South Africa to earn his living as a storekeeper in the back of beyond. A strange encounter on the journey suggests that dark deeds and treacherous intrigues are afoot – all bound up with the mysterious primeval kingdom of Prester John.