This is a historical account of a shipwreck, the devolvement of military discipline into competing factions of the remaining crew, the return to England of the different factions, and the subsequent court martial. Grann does a good job of entertaining as well as educating the reader. 

(I used this to fill the prompt, "A book with an unreliable narrator." Doesn't really fit that description, although each of the factions had a different story to tell upon their return to England.)