The story opens with John Jameson, son of J. Jonah Jameson, seeing Spider-Man from the window of a high-rise restaurant. The appearance of Spider-Man unnerves the former astronaut, who is trying to forget that he once was the monster known as the Man-Wolf. Back in Amazing Spider-Man #125, we learned that a strange moonstone that John found on a lunar expedition transformed him into the savage Man-Wolf. Spider-Man apparently put an end to his torment by ripping the moonstone from around John's neck and throwing it into the Hudson River. John tells his fiancée Kristine that he isn't feeling well. "It's that flu virus going around; I'll be okay tomorrow," he tells her. But after she leaves, he starts to feel as though he may change back into the Man-Wolf. "But that's impossible...I don't have the moonstone any more," he thinks.

Meanwhile, Peter Parker drops by the Daily Bugle office, where Joe Robertson tells him about a string of murders along the east coast. The pattern has the murderer heading to New York City. "Every victim was discovered drained completely of blood," the Bugle's city editor tells Peter. "And possessing two small puncture wounds on the neck." Robertson also has a photo of Morbius (last seen in Marvel Team-Up #4) at one of the murder scenes. The world doesn't know he has become the living vampire, but Robertson recognizes him as the Nobel Prize-winning scientist Michael Morbius, who is believed to be dead.

John Jameson stumbles into a diner, where he does indeed transform back into the Man-Wolf, even though he doesn't have the moonstone that caused his original transformation. He starts prowling the streets, although not aimlessly. Something draws him to a waterfront warehouse...where Morbius awaits! It turns out that Morbius pulled the moonstone out of the river and has secretly been following John, exposing him to its radiation in order to transform him back into the Man-Wolf, Now, Morbius places the moonstone pendant around the Man-Wolf's neck and bites him with his fangs, putting the Man-Wolf under the living vampire's complete control. "And with your unwitting aid...Morbius will succeed in this, his most considered plan!" he says. That plan is quite simple: He believes Professor Ward, a researcher at Empire State University, may have developed a cure for the condition that transformed him into a living vampire. He plans to use the Man-Wolf to keep Spider-Man occupied while he confronts Ward and takes the cure. However, Peter Parker, who is an ESU student, spots the deadly duo on campus and suits-up as Spider-Man. He battles the Man-Wolf and manages to outsmart his bestial foe by luring the Man-Wolf into a web. From there, Spider-Man goes to Professor Ward's office, where he learns the doctor is developing a procedure to completely replace a person's blood. Spider-Man leaves, but he's come up with a plan.

An hour later, Morbius appears in Professor Ward's window. "Where in Heaven's name have you been, man? And what do you want from me?" the startled scientist asks. "I've been in Hell, Professor Ward -- and I've come to you to release me!" Just then, Spider-Man ambushes Morbius from the ceiling. Professor Ward warns him that the equipment in the room is irreplaceable. Spider-Man and Morbius fight and before long, the equipment is completely destroyed. "You fool--we've destroyed it!" Morbius screams. Without it, Morbius realizes there's no sense in hanging around to fight, so he flees. However, Spider-Man has outsmarted him. He and Professor Ward replaced the real equipment with some spare parts, knowing that Morbius would leave if he thought the experiment had be ruined. Spider-Man will have to deal with Morbius again, but at least for now, he won't be around to menace Professor Ward.

The story ends with Spider-Man dropping by J. Jonah Jameson's office to warn the Bugle publisher that John Jameson has once again become the Man-Wolf. Jonah doesn't want to hear it, though. He dismisses Spidey in his typically abrupt manner. "Either I've made a terrible mistake and I'm sorry," Spider-Man says. "Or you're a bigger fool than I ever thought you were -- and you're the one who's going to be sorry. You and your son." It turns out that Jonah is fully aware that his son's curse has returned - and he has no idea how to deal with it.