The novel begins with explorer Robert Walton looking for a new passage from Russia to the Pacific Ocean via the Arctic Ocean. After weeks as sea, the crew of Walton's ship finds an emaciated man, Victor Frankenstein, floating on an ice flow near death. In Walton's series of letters to his sister in England, he retells Victor's tragic story.
Growing up in Geneva, Switzerland, Victor is a precocious child, quick to learn all new subjects. He is raised with Elizabeth, an orphan adopted by his family. Victor delights in the sciences and vows to someday study science. Victor prepares to leave for his studies at the University of Ingolstadt, when his mother and Elizabeth become ill with scarlet fever. Caroline dies from the disease, and Elizabeth is nursed back to health.
At the university, Victor meets his professors M. Krempe and M. Waldman. For two years, Victor becomes very involved with his studies, even impressing his teachers and fellow students. He devises a plan to re-create and reanimate a dead body. He uses a combination of chemistry, alchemy, and electricity to make his ambition a reality.
After bringing the creature to life, Victor feels guilty that he has brought a new life into the world with no provisions for taking care of the "monster." He runs away in fear and disgust from his creation and his conscience. The monster wanders the countryside while Victor seeks solace in a tavern near the university. Henry Clerval appears to save Victor and restore him to health.
Alphonse writes to Victor telling him to come home immediately since an unknown assailant murdered his youngest brother, William, by strangulation. Justine Moritz, their housekeeper, is falsely accused of the murder of William, and she goes to the gallows willingly. Victor knows who the killer is but cannot tell his family or the police. He journeys out of Geneva to refresh his tortured soul and visits Mount Montanvert when he sees the monster coming to confront his maker with a proposition"make me a mate of my own." Victor refuses, and the monster asks that his part of the story be heard. The pair retreats to a small hut on the mountain where the monster tells his story.
The monster has taught himself to read and understand language so that he can follow the lives of his "adopted" family, the De Laceys. While the monster wanders the woods, he comes upon a jacket with a notebook and letters that were lost by Victor. From the notes, the monster learns of his creation. He has endured rejection by mankind, but he has not retaliated upon mankind in general for his misfortune. Instead, he has decided to take revenge on his creator's family to avenge the injury and sorrow he endures from others.