"He had come like a thief in the night." is taken from the Bible, specifically Thessalonians 5:2. It refers to the second return of the Lord (Jesus), that means another one from the one we know. The first one is his rebirth after beeg crucified. He will return as "a thief in the night" because we don't know when it will happen, he won't announce it.
Answer: be brief to get interest but not narrowed, there is introduction ( first paragraph) and body (as much of paragraphs you wanna write max: 4 to 5) and lastly the conclusion where you make a small summary of the writing
