Basic Plot Outline
Peter Parker (Michael J Fox) is your classic late 80's child. He doesn't know where he's going in life, he doesn't belong to any social group, he's not terribly bright or awfully stupid, and to complicate matters, his scientist parents have disappeared under mysterious circumstances.
He moves in with his Aunt May and Uncle Ben (played by Anne Bancroft and Gene Wilder respectfully) who notice Peter is more withdrawn and depressed than most people his age. They encourage him to expand his social circle and soon falls in with Harry Osborne and Mary Jane Watson.
Needing a few extra dollars to help pay his aunt and uncle's rent, Peter volunteers to become a test subject for a new drug called "Crepsa" which has been touted as a cure for cancer.
When Peter is taking his daily dosage of Crespa one day, Peter ingests a spiders egg and his body begins going through physical and psychological changes.
Firstly, he starts developing a taste for flies and other such insects, he curls up into a ball when cornered, and his fingers begin to elongate and curve outwards, much like a spider's legs.
Peter discovers he can climb walls and shoot web out of his hands, and decides to become a vigilante to rid his community of crime, and make a few dollars on the side.
In a sub-plot, Dr Otto Octavius is head of research of OsCorp's artificial limbs department, and while working late in the laboratory one night, he is exposed to a biological weapon OsCorp is developing for the United States government, a weapon that grants the user the ability to manipulate limbs by the power of the mind.
Octavius falls into a coma and awakens in a hospital and murders all the staff present when demonstrating his new found abilities, and breaks loose forcing him into a showdown with Spider-Man...
Parker decides to take up the mantle of the "Spider-Man" and is successful in stopping crime in his community, however the effect of being a half-human half-spider hybrid is destroying him both emotionally and physically.
In a now infamous scene, Peter Parker accidentally wraps his girlfriend in a spider-web while in the middle of intercourse, while the scene was played for laughs, this scene was the reason the film was initially given an R-rating by the MPAA, however it was later reduced to a PG-13 after all careful editing.
The final showdown between Spider-Man and Dr Octopus takes place in Central Park, after Dr Octopus kills his Uncle Ben off-screen and has his Aunt May held hostage. Spider-Man, now feeling the effects of the metamorphosis spits venom into Dr Octopus' eyes, blinding him and dropping his Aunt May.
By now, half of Peter's face is covered in spider's skin, he has grown two additional spider like legs, and his teeth have become fangs.
Upon seeing the coverage on the television and feeling guilty for what he's done, Norman Osborne develops a cure for Peter, while the physical effects are no longer visible on his body, he will still keep the abilities he's gained.
Peter, now satisfied the nightmare is over continues attending high school, helping his Aunt May around the house and re-ignites his relationship with Mary Jane as credits roll.
However in an end credits scene, we see Norman Osborne at his desk interviewing a somewhat skittish and crazy looking man. The crazy man gives a monologue about how lizards are nature's perfect hunters and that he could apply the lizards features to humans for military purposes.
"Welcome to Oscorp, Dr Connors" says Osborne as he shakes hands with Kurt Connors and the film smash cuts to black.