Dr. Otto Octavius tries to complain to his boss Norman Osborn about the dangers of several recent experiments they have been performing to create super villains in his laboratory, but is quickly berated by Osborn for his "whining." Octavius backs down and goes to work inside an experimentation chamber while Osborn departs. Unbeknown to him, the villain Green Goblin sneaks into the lab, activating the chamber's generators while locking Octavius inside. While unsuccessfully trying to escape from the chamber, the radiation emitted fuses the mechanical tentacles he is wearing into his skin.
Osborn and others arrive on the scene to turn off the generator, while Spider-Man jumps in to help get Octavius out of the wreckage. When the doctor wakes up, he attacks Osborn with his tentacles and pins him to a wall. When Spider-Man tries to intervene, Octavius brushes him aside as well with one of his tentacles, declaring himself "Dr. Octopus." He steals a power battery to recharge his tentacles and storms out of the building, using his tentacles as extra limbs. The next day, Peter, Gwen, Harry and some of Harry's new popular friends go to Coney Island, where Harry impresses everyone with his newfound strength. Liz Allan begins to attach herself to Peter and the two have a fun time. However, Peter spots Dr. Octopus and abandons the group to pursue him as Spider-Man.
Spider-Man follows Dr. Octopus to TriCorp, where he attempts to steal a power pack from a vault. Spider-Man swoops in and gets to the power source before him. He then runs out, with Dr. Octopus pursuing him, hoping to cause the doctor to run out of energy. They reach Coney Island through their ensuing brawl and Octopus, aware of Spider-Man's desire to save innocent lives, kidnaps Liz. With only an hour of energy left, he climbs to the top of a roller coaster, forcing Spider-Man to choose between the power pack and Liz. Spider-Man throws the pack in the air before rescuing Liz; he gets close to Dr. Octopus as the latter scrambles for the power pack and is able to take it away from him, successfully defeating the doctor.
When Peter returns to the group, he discovers that Liz is breaking up with her boyfriend Flash Thompson after the latter gets jealous that she spent the day so close to Peter. Gwen approaches Peter, and the two agree they need to have a talk with Harry about his belligerent attitude towards them and constant strange behavior.