Peter discovers that his biology professor, Dr. Miles Warren, has a few loose screws. As the Jackal, Warren reveals his love for Gwen Stacy and the secret behind her resurrection. Will Spider-Man be able to talk sense into his professor before Jackal takes Ned’s life?
At the end of the previous issue, the Jackal pulled off his mask to reveal himself as Professor Warren, Peter Parker's biology teacher, whilst Spider-Man was falling unconscious. Spider-Man falls to the ground, exhausted, and in his drugged state, remembers the past day (which basically recaps the previous issue). When Spider-Man wakes up, he finds himself in an abandoned tenement, strapped to a table. The Jackal approaches him, and tells him not to spoil his moment of triumph. Spider-Man breaks through the straps binding him to a table, since they're not too strong, but is surprisingly defeated by the Jackal quite easily. The Jackal then tells Spider-Man that before he kills him, he'll tell him why he hates him.
The Jackal then explains that he hates Spider-Man since he was loved by Gwen Stacy (as Peter Parker, although it's never explained how the Jackal found out that Peter was Spider-Man), and she was killed because of him. He explains that he'd always admired Gwen, more than he would admit, and felt protective towards her. Upon here death, he became slightly depressed, until his assistant Anthony Serba showed him a successful cloning experiment. Professor Warren then gave Serba some tissue samples from an experiment in his class, for him to clone. However, when Serba found out the clones were human, Professor Warren accidentally killed him in his haste to keep him silent.
Professor Warren was so shocked by the murder that he disposed of Serba's body, and tried to convince himself that it was somebody else who was the murderer. As he passed a lecturer talking about jackals, Professor Warren convinced himself that the Jackal had been the one who killed Serba. He then spent the next few months developing his Jackal gear, training himself, and taking care of the clones. Upon Gwen Stacy's clone being complete, the Jackal used hypnosis to make her believe she was the real Gwen. In the present, Spider-Man tells the Jackal how sick he is, to which the Jackal runs away, telling Spider-Man to meet him at Shea Stadium that night for their final showdown.
Spider-Man heads to the Daily Bugle, hoping to see Mary Jane alone, but finds Betty Brant crying, since Ned and Gwen are missing. When J. Jonah Jameson notices Peter Parker, he yells at him to go find Ned. Later that night, Spider-Man heads to the stadium where the Jackal told him to meet him, but is ambushed upon arrival by the Jackal. The Jackal knocks him out, and injects him with a syringe as he falls unconscious, saying it's all necessary. When Spider-Man wakes up, he finds another person in exactly the same costume as him, speaking simiarly to him. The Jackal explains that Peter Parker was also cloned, and that only one of the Spider-Men is the real one. He adds that even though both of them believe themselves to be the real Spider-Man, only one is, and only that one can save Ned Leeds (who's attached to a bomb).
Both Spider-Men start fighting over which one of them is the real Spider-Man, with the Jackal and the Gwen Stacy clone watching. After a bit of fighting, the Spider-Men realize that they'll never work out which of them is which through fighting, and they go off to save Ned. As they do, Gwen Stacy's clone rips off the Jackal's mask, telling him that she's realized he's a murderer. Upon hearing his beloved Gwen calling him a murderer, the Jackal realizes what he's become, and runs over and saves Ned. However, the bomb is still set to blow, and explodes. One of the Spider-Men is still alive, along with Ned and Gwen's clone. However, upon the clone asking Spider-Man how he knows that he's not the clone, he realizes that he doesn't know, and could simply be a clone.
The next day, Gwen's clone says goodbye to Peter at a graveyard, telling him that she's not the true Gwen Stacy, and can't pretend to be. Peter then goes home to find Mary Jane in his apartment, and tells her how happy he is to see her.