A story's plot consists of the chronological series of events that occur in it. Plot is different than theme, which deals with the bigger ideas a story seeks to explore. Often, readers confuse plot and theme when thinking of what a story is about. To find a story's plot, you must pay close attention to the events of the story.
Read the story slowly, paragraph by paragraph. Each time an event occurs that moves the characters forward in some way -- either moving them to a new place or to have a new conversation or experience -- draw brackets around the passage.
Number each passage you have bracketed. This will help you create a timeline of the story's plot.
On a sheet of paper, number and list the events of the story, from the beginning all the way to the end. This will comprise a plot outline, which will tell you the exact plot of the story, without switching focus to theme, setting or symbols.