At the start of this issue, Spider-Man is swinging around town, complaining about how he has a cold, when he notices two police officers investigating a break-in at the museum. The cops notice that the door was broken from the inside out, whilst Spider-Man remarks that the thief would have gotten in through a broken skylight, which has been scorched by some sort of heat. Inside, the cops also notice that some almost worthless rocks have been stolen, when some valuable jewels are nearby. Spider-Man also notices that some footprints have been burned into the ground, when the cops notice him and chase him off. Spider-Man changes to his alter ego of Peter Parker, but doesn't notice a mysterious woman recognizing him.
At an apartment nearby, a woman is cleaning up a room when the resident walks in. Upon seeing someone else in his room, he yells at the woman to get out until she leaves. The woman then calls up the Daily Bugle, saying that she has a story for them. Meanwhile, the mysterious woman who recognized Peter before turns out to be none other than Liz Allan, his high school sweetheart. After a short talk, Peter takes Liz back to Mary Jane's apartment, where she falls asleep.
At the Daily Bugle, Ned Leeds receives the phone call from the cleaning woman, and heads over to the apartment. When he gets there, there is a massive explosion. Emerging from the explosion is a man, who comments on how he's failed and is doomed to remain a monstrosity. As he talks, his feet burn into the linoleum. Ned then runs up to the top floor, where he finds the woman who called him unconscious. The man then approaches him, and tells Ned that he must die.
Meanwhile, Peter Parker heads to the Daily Bugle, where Robbie tells him to go after Ned and get some photos for the lead he was following. Peter changes to Spider-Man, and upon reaching the apartment where Ned is, finds Ned unconscious with some bad burns on his neck. Spider-Man is then attacked by the Molten Man, his old enemy from years ago. The Molten Man tells Spider-Man that his body has evolved, and is now flaming, unlike in their previous fights. Spider-Man and the Molten Man then fight, but during the fight, the Molten Man falls out of the window of the apartment, and onto a fire hydrant. The heat from the Molten Man's body causes enough steam for the Molten Man to get away in the confusion.
Spider-Man then grabs Ned Leeds and starts heading for a hospital, whilst Ned mumbles about glowing rocks. As Spider-Man changes to Peter Parker, he notices that Ned is getting harder to carry, and that he is starting to feel sick. Upon reaching the hospital, the doctors realize that Ned has radiation poisoning, and Peter realizes that the Molten Man must have stolen the rocks from the museum, and that they must have been radioactive. As Peter walks off, he feels more and more sick, and realizes that the radiation from the rocks has affected his own radioactive blood, and that he's being poisoned by his own blood.