As next in line to be king of Saudi Arabia, Mohammed bin Nayef was unaccustomed to being told what to do. Then, one night in June, he was summoned to a palace in Mecca, held against his will and pressured for hours to give up his claim to the throne.

By dawn, he had given in, and Saudi Arabia woke to the news that it had a new crown prince: the king’s 31-year-old son, Mohammed bin Salman.