Frankenstein: Or, The Modern Prometheus is framed as a series of letters written by polar explorer Robert Walton to his sister, Margaret Saville, who is home in England. He relates to her his adventures, including a story told to him by a young man, Victor Frankenstein, whom his ship has rescued from the polar ice.
As a young university student at Ingolstadt, in Bavaria, Frankenstein is determined to find the secret of life. He studies constantly, ignoring his family back in Geneva, Switzerland. He steals body parts from charnel houses and medical laboratories, then uses the power of electricity to create a living being. He immediately knows he has erred: His creature is ghastly. It leaves Frankensteins quarters, but not his life.
Frankenstein next sees the creature back in Geneva, where he has returned following the death of his young brother William. Although a servant girl, Justine, is accused of causing Williams death, Frankenstein sees the creature lurking near the place of the murder and knows he is the killer. Frankensteins anguish is intensified when innocent Justine is executed for the murder. In his agony, Frankenstein leaves home to wander in the mountains. The creature confronts him and tells him his own story.
After leaving Ingolstadt, the creature wandered throughout the countryside. He discovered quickly that he was frightening and repugnant to humans and took to traveling at night and hiding during the day. The creature learned to speak and to read during a long stay in a hovel attached to a poor farm familys hut. During his stay, he performed many kindnesses for the family and felt sympathy for their poverty. He befriended the old father, who was blind. As soon as other family members returned and saw him, they fled. In anger, the creature set their farm on fire.
He made his way to Geneva, saving a small child from drowning along the way. Every time he tried to perform an act of kindness, however, he caused a reaction of horror. On the mountaintop, the creature begs Frankenstein to make him a mate so he need not be lonely. Then, he says, he will leave humankind alone and live with his mate in seclusion. If not, he says, he will be with Frankenstein on his wedding night.
Frankenstein promises to make him a mate but questions his wisdom. He travels to England with his friend William Clerval, then goes alone to an isolated spot in Scotland to carry out his promise.
He cannot finish the job. He abandons it and prepares to return home. The creature, infuriated by Frankensteins unwillingness to keep a promise, kills Clerval, then returns to Geneva to kill Frankensteins bride, his adopted sister Elizabeth, on their wedding night.
The tragedy and the guilt are too much to bear. Frankenstein resolves to pursue the monster until one of them is dead. He travels by dogsled across the snowy expanses of Russia toward the North Pole. He is picked up by Robert Waltons ship during his pursuit and dies on the ship after telling Walton his story. The creature appears and tells Walton of his remorse for his deeds, then sets off into the cold to build his own funeral pyre.