Answer:
The narrator, a newspaper correspondent, is traveling across India by second-class train when he meets Peachey Carnehan, a white man planning to extort money from a local prince. Carnehan asks the narrator to deliver a message to his friend, Daniel Dravot. The narrator agrees to do so because he and Carnehan are both Masons.
A few days later, Carnehan and Dravot turn up at the narrator’s office. They are planning an expedition to conquer Kafiristan, and they would like the narrator to provide them with books and maps to plan their journey. The narrator says that Carnehan and Dravot are fools and will likely die before they reach their goal. However, Carnehan and Dravot explain that they have signed a contract: neither of them will have anything to do with women or alcohol until they have become kings of Kafiristan. This contract, they believe, demonstrates that they are in earnest. Reluctantly, the narrator agrees to help them.
Explanation:
https://www.litcharts.com/lit/the-man-who-would-be-king/summary