Frankenstein is a frame tale. What this means is that it is a story within a story, involving a change in narrators. A traditional frame tale has two narrators, but there are three narrators in Frankenstein. The first is Robert Walton, who writes several letters home to his sister, Mrs. Saville. The second narrator is Victor Frankenstein himself, who tells us the story of his young life and of his growing fascination with the idea of reanimating the dead. It is through Victor that we learn of the creature’s creation and his initial “birth.” It is also through Victor that we learn of his horror when the creature comes to life and his mental instability as a result. The third narrator is the creature himself. The creature tells us the story of loneliness and rejection, of revenge and sorrow.
Robert Walton comes back at the end of the story to relate to the reader not only the being forced to turn back and abandon his journey, but also the death of Victor Frankenstein and his creature. This also serves to close out the “frame.” In other words, Robert Walton started telling the story, and he finishes it at the end, creating closure to the frame tale.