The main plot of 'the bottle short story' could vary widely. It might be about a person who finds a mysterious bottle on a beach. Inside the bottle could be a map leading to a treasure, or a letter from a long - lost relative. The story could then follow the protagonist's quest to uncover the secrets of the bottle and how it changes their life.
I'm not sure as I haven't read it specifically. But generally, in a short story about a bottle, it could be about something hidden in the bottle, or perhaps a journey that the bottle undertakes.