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. 

Written as a boys' own adventure story and set mostly in South Africa (where Buchan had worked), Prester John was published in 1910 when Buchan was 35. It's a fast-moving thriller in the style of Robert Louis Stevenson and Rider Haggard.