Answer:
The words "strangest" and "unusual" suggest that the narrator is about to tell the story of an odd or puzzling group of people.
Explanation:
The Great Gatsby, by F. Scott Fitzgerald, is not a story about a pleasant neighborhood or a political revolution. It is indeed a story about an odd group of people. The characters, most of them rich and somewhat famous in their social circle, are broken people.
The narrator, Nick, is cousin to Daisy, the love interest of the main character, Gatsby. Nick is the only one who seems unable to adapt to the other characters' vain lifestyle. He is capable of watching their stories develop only to reach a somber conclusion. Morals and happiness are kept at bay by the vanity and selfishness of the richer portion of society. They are truly miserable, even if they appear to be enjoying themselves. There is no love between husband and wife, mother and daughter, or between friends.
Nick himself ends up walking away from the others, disgusted by the falsehood of their lives.
