Spider-Man is trying to patch things up with MJ. Gwen is trying to get Peters attention but ends up creating a strong friendship with both MJ and Peter
Meanwhile Doctor Connors is trying to recreate his arm..... He notices that part of the symbiote expands in a way his cells could just like reptiles.... using his investigation on reptiles and the discoveries found in the symbiote (remember Connor has a piece). By combining the two he injects himself creating himself the Lizard an uncontrollable creature seeking out destruction......
Casually the new found friends MJ, and Gwen go to the university to pick up a book Gwen forgot they enter Connors class and find the Lizard trying to kill the... During the screaming and running away the vial holding the Symbiote falls to the ground and breaks. MJ discreetly calls Peter in search for Spider-Man (this could be while she is hiding under the desk or something) Spider-Man arrives to save the day but the Lizard escapes.... During the fight Spider-Man gets a huge cut from one of the claws of the Lizard on his back....and the Symbiote is attracted by the Spider's blood......
Spider-Man leaves and Gwen and MJ are safe but back at home while Peter is cleaning his wound leaving a lot of blood lying around.... The Symbiote merges with the blood (making it Red FYI I'm taking a lot from Ultimate Spider-Man). Then on the news there is a new Serial Killer in town named Cletus Kasady so Spider-Man is on the job..... The now red symbiote with no host is weakened but sticks to Parker without his knowledge. Spider-Man Catches the Serial Killer and throws him in jail..... Kassady having this new found hatred for Spider-Man merges with the Sybiote to make Carnage and kills his way out of jail.....
The Lizard and Spider-Man have a couple of more rounds before Spider-Man realizes his teacher is actually the Lizard.....
During class Gwen and Peter get a new substitute teacher: Professor Miles Warren
Anyways..... Peter figures out a way to take the Connor out of the Lizard and cures him.... The new Professor falls for the Blond in his class and tries to get Connor to leave the class permanently so he could keep teaching the class Warren kidnaps Connor so he wont interfere in what Warren thinks is true love......
MJ and Peter's relationship is growing once again.....
Felicia Hardy a new girl in school keeps bumping into Peter..... At the same time a new vigilante comes into town: Black Cat....
Spider-Man and Black Cat finally meet and Spidey questions Black Cat's alliance.... She doesn't answer and says that if Spider-Man catches her then she will answer the question..... They play tag for a while and then she says that she is only "complicated"
Black Cat on her crime spree finds a man who seems familiar.... Felicia Hardy's science teacher kidnapped by a crazy man...... She saves him making Spider-Man a little precocious about if Black Cat is good or Bad (Black Cat flirts with the Spider a little and disappears into the night)
Carnage and Spider-Man fight it up a bit Carnage revealing himself to the world... Carnage being a name J. Jameson comes up with in the Bugle!!!
Spider-Man figures out the carnage is the serial killer..... Peter realizing that he is no match for this new villain seeks help from Connors and he discovers sonic weaponry is the way to go.... meanwhile they bust heads once more and the Police surround the area where they fight... (where? Who knows but its big)
Gwen is out having lunch with her dad and Capt Stacy gets a call to go there .. Gwen goes with him...
MJ is at Aunt May's house having some pie and see the whole comotion on television.....
They have a huge ending battle and during the battle Carnage is on the verge of pummeling Spider-Man.....
During this MJ whispers "No, Peter" and there's a reaction to this by Aunt May (So now she know or thinks she knows who Spider-Man is)
Professor Connors arrives with his sonic weaponry but Captain Stacy doesn't allow him to go through........Connors fight hims over it and then both of them are caught in the battlefield......
Carnage only seeking destruction heads first for Connors and Spider-Man swings on over and saves him... leaving Stacy out there alone....
Relentlessly Carnage kills Captain Stacy just when Spider-Man is abut to save him..... Spider-Man on an adrenaline rush he starts hitting Carnage relentlessly... Gwen goes into the battle field and cries over her father's death. Connors the uses the sonic weaponry and "destroys" the creature....
The ending scene is a lot like the ending from the first movie.... At Captain Stacy's funeral Peter goes over and hugs the pale Gwen..... Gwen the mentions her hatred for Spider-Man because he could have saved her father but he didn't he left him alone there to die.......
After the funeral Peter and MJ walk alone through central park and MJ mentions the proposal he had planned (Spider-man 3) and mentions that although they might not be ready for that they could start things over to where they left off...... Peter walks MJ home... At her doorstep he kisses her and whispers to her "I love you"
Then he turns around about to leave.... MJ then stops him and invites him in.......
The scene ends with a mashed up Cassady on the ground recreating himself as Carnage.........
Black Cat watches over this
Miles Warren then walks through his apartment and enters a room where he has a shrine for Gwen Stacy...... He talks to a huge picture of her and says: "we will be together" then the camera zooms into his eyes and the effect turns green (jackal-wise) the screen turns black and you can hear him laughing (setting up the environment for Spider-Man 5)