Spider-Man is tossed out the window of a skyscraper but then catches himself and swings back into the building, where the members of a fancy-dress party are being held hostage by men in pumpkin masks. Spider-Man prepares to face his newest opponent: the Green Goblin. He flashes back to how things began...
It's the night of Midtown Fall Formal and Harry arrives with Gloria and the rest of Flash's gang. They seem to have embraced him as one of their own, due to his having spent a lot of money on them and provided a limousine to get them to the dance. He snubs Gwen so he can hang out with the "cool crowd," but gets one-upped when Peter arrives with his neighbor Mary Jane Watson along with him.
J.Jonah Jameson is at the Bugle preparing to go out for the night with his son, Air Force Colonel John Jameson. John just wants a quiet night with his dad, but Jonah has other plans. As he leaves, Robertson suggests that reporter Ned Lands follow up on his plan to find out Spider-Man's secret identity, despite the fact Jonah would rather keep Spider-Man's identity a secret to avoid giving him any public sympathy.
Peter introduces Mary Jane to Harry and the others, and Flash tries to break them up by saying he and Peter had a bet to see if Peter could find a date. Peter admits to it but Mary Jane isn't phases and congratulates him, then goes to dance. Harry goes to get some drinks but overhears Kenny asking Gloria to give him one more chance. She agrees and Harry crushes the glasses in his hands. He then goes to his locker and takes out an OsCorp test tube containing a "Goblin" formula, and drinks it.
Otto Octavius is working late at the OsCorp conversion laboratory when a green-skinned figure breaks in and steals a high-tech experimental glider. He flies off and attacks some robbers, casually knocking them aside. He knows that they are working for the BIg Man and tells them that they're going to work for him now. He smashes open the safe and gives them their money, then tells him he plans to take down the Big Man and they're going to help.
The Big Man is hosting a black-tie party in his role as philanthropist L. Thomas Lincoln. Jonah brings his son along, but John tries to convince him he'd rather just have dinner. The robbers now working for the Green Goblin burst in, wearing pumpkin masks. They hold everyone prisoner and the Goblin arrives to tell Lincoln to surrender or he'll tell everyone he's the Big Man. Lincoln is unimpressed and tells his men to take care of the intruders. However, the Goblin's high-tech weaponry is more then a match for them. He also disarms John Jameson when the colonel tries to fight back. Jonah calls Robertson and says he'll cover the story hinmself (to save money), but they should send Peter Parker to take photos.
Robertson reaches Peter at the Formal and he has to inform Mary Jane that he has to go to work. Mary Jane is okay with it and tell him to get back when he can. Peter arrives at the black-tie party as Spider-Man and the Big Man greets him, saying he's happy to get rid of the intruder. Spider-Man thinks the Green Goblin is working for the Big Man but the Goblin assures him he isn't and suggests they join forces. Spider-Man turns him down and they fight.
Now, while Spider-Man takes on his new opponent, the King and Queen of the Prom are crowned at Midtown. Flash is elected King and the Queen is... Mary Jane. The other girls aren't happy.
Spider-Man latches onto the Goblin's glider and is pulled outside and then the villain cuts the line. Spider-Man is out of web fluid but manages to reload as he falls, then swings through the streets with the Green Goblin in pursuit. Spider-Man manages to defeat the villain with one of his own bombs and snare him in a web. However, the Goblin warns him that he planted a bomb at the party and Spider-Man is forced to go and find it. He returns and points out to the Goblin's henchmen that the'll be blown up as well. They leave along with the partygoers and Spider-Man finds himself working with the Big Man to find the bomb. John gets his father to return as well, realizing that the Goblin hid it in the chandolier when he broke in. Spider-Man recovers it and shoots it up into the sky with a web catapult, and it detonates leaving a goblin-shaped cloud of smoke. The Big Man thanks Spider-Man, noting that he offered to pay the hero to do what he did for free. An angry Spider-Man leaves.
Afterward, John convinces his father not to report his part in the story, since the investigation could force his superiors to take him off his current mission. Jonah reluctantly agrees and takes out his anger on Peter, who never showed up. However, when he calls into the Bugle he finds out that Peter has already e-mailed photos of Spider-Man in action.
Flash and the others figure that Harry has abandoned them, since he sent the limo away and has disappeared. They don't know that Harry is watching them from a nearby alleyway, contemplating a nearly empty tube of the Goblin formula. He turns and walks off.
Peter arrives back at Midtown and finds Mary Jane dancing with another boy. However, she smiles and reassures him that she saved the last dance for him.