Victor Frankenstein was very interested in natural philosophy and chemistry and basically tried to play G-d by creating life. When he found the secret of activating dead flesh, he created a superhuman being composed of rotted corpses. What he did was considered unthinkable, and he was haunted by his own creation.
When the monster escaped, Frankenstein knew that he had to deal with the consequences of what the monster might do. Frankenstein received a letter one day which informed him of his younger brother William's murder, and immediately suspected that he was responsible, for he was the creator of the hideous monster. A friend of the family named Justine Moritz was the "presumed" murderer, and Frankenstein was determined to prove her innocent. Circumstantial evidence, however, led the courts to believe Justine guilty, because found in her pocket was a photograph which had belonged to William.
Justine had been put to death, and Frankenstein had yet to find his creation. Finally, upon their meeting, the monster confessed to his creator of what he had been through, how he was rejected by society, and finally, how he had come to kill William. When William had revealed his name to the monster, the monster immediately figured that by killing the young boy, he would have revenge on Frankenstein for giving him life. The monster did not understand the concept of right and wrong and he especially didn't mean to kill anybody. His expression of anger ended up being violent, even fatal to the victim, and it just worked out that he killed people.
As the monster's story continued, he demanded of Frankenstein a female mate who he can be with until his end, and promised to live away from society. Frankenstein, meanwhile, tried to restore...