What plot exposition does Shelley offer the readers in chapter 1 and 2?

The bulk of the plot exposition is in the form of letters written between explorer Robert Walton and his sister, Margaret Saville, telling the story of Frankenstein and his monster.

Hey, I'm not sure if you meant Letters 1 and 2 or Chapters 1 and 2. In the chapters, Victor is just sad on his deathbed giving us the background of his sad life and how he got to this point. You know, ramblings of a near-dead guy about the good old days when he created a hideous monster that killed everybody he knew!