Three steps to finding a theme in a story are: 1) Identify the plot, which is what the story is about. 2) Determine the meaning behind the story, usually an abstract result of character's actions. 3) Express the theme as a lesson about human nature. For example, a story about a man hunting down his family's killers could mean that when the justice system fails those who have lost everything, they will go to extreme lengths, with the theme being people with nothing left to lose can be dangerous.