what are the themes in the story?how do they relate to the plot and characters ?an

Certainly at the heart of the French Revolution is the theme of class struggle,

"Dickens chooses a side, ultimately showing opposition to the Revolution due to the ruthless and uncontrolled force of its aroused mobs. Even so, the story of the Marquis's rape of the peasant along with other details of aristocratic mistreatment of the lower classes provide some justification for the goals of the French mob. In the end, he portrays the mob as having moved beyond the pale to a degree beyond what happened in England; the French mob acts with such force that it resembles a natural element like fire or water."

There are others like fate, mob mentality, doubling, and social injustice but I think they merely support the class disparity that fuels this revolution. Please check to the GradeSaver lining below for this excerpt and more detail.