Once the Church had become fairly well established in the land of Ishmael under the sponsorship of King Lamoni, he was anxious to take Ammon to the headquarters or capital of the Lamanite world, which was at the city of Nephi. At first Ammon thought this was a wonderful break to have Lamoni introduce Ammon to his father, the king of all the Lamanites, but something abruptly changed his mind. Here is the story.
In this revelation Ammon was told four things. First, he was told not to go to Nephi. Second, he was told that if Lamoni introduced him to the king of the Lamanites, the wicked ruler would try to kill Ammon. Third, he was told that three of Ammon's missionary companions were in serious difficulty. They had been captured and imprisoned in the land of Middoni. And fourth, Ammon was told that he should leave immediately to go to Middoni and help rescue his fellow missionaries, which included his brother Aaron.