Setting: In a city by the ocean. I think the time period is around 18-19th century since there was an Industrial Revolution.
Conflict: The lost thing vs. Society
Climax: The lost thing finds a place where he used to live and goes back to it.
Symbol: A key symbolizes a path to a wonderful place.
Irony: Even though the lost thing is very big, nobody seems to care.
Theme: You always have a place to belong.
