The people who made the most money during the Gold Rush were "opportunistic" shopkeepers. Someone who is opportunistic is someone who is able to take advantage of any opportunity that presents itself. The word has a negative connotation, as it suggests that someone takes advantage of an opportnunity regardless of consequences or principles.
Answer: Plot is the events of story; theme is the meaning behind or revealed by story. Theme is sometimes defined as the moral of a story, though theme doesn't have to be a moral. Morals that double as theme include these: cheaters never win, honesty wins the day, and good guys finish first
