It is night and a light snow is falling as Spider-Man web-swings by the Metropolitan Museum of Art on December 22. He lost track of time at Cissy's, and now he has to hurry to the Daily Bugle to meet Joe Robertson as he promised. Inside the museum, the guard, Gus Hovannes, contemplates the now empty building. A short time before, the place was wall-to-wall people because of the new exhibits, but now Gus feels a bit lonely as he makes his rounds. Suddenly, he sees a moonbeam reflect off an amulet in one of the cases. Then a bright light assails his eyes, and a voice in his mind commands him to shatter the case and put on the amulet. When he breaks the glass with his gun, he cuts his hands, and the blood drips onto the amulet's gold chain. Then he begins to utter words in a language that has been dead for 9,000 years.
Spider-Man enters the Daily Bugle building through a window and quickly changes into his street clothes. Then he enters the city room, where a Christmas party is in progress. Among the attendees are Joe Robertson, Gloria Grant, Marla Madison, and a certain mild-mannered reporter for a great metropolitan television network. J. Jonah Jameson asks Peter whether he received his Christmas bonus, and Peter wryly thanks Jameson for the extra ten dollars. Then Mary Jane Watson, whom Peter has not seen in some time, walks up and plants a big mistletoe-kiss on him. Suddenly, Robertson receives a phone call about trouble at the Metropolitan Museum. Because Peter and Charley Snow are the only two staffers present who do not drink, Robertson asks them to cover the story. In minutes, a Bugle radio car is on its way, carrying Peter, Charley, and an unexpected stowaway, Mary Jane. When they arrive, they find the museum surrounded by a crowd. Flashing their press cards, Charley and Peter get through the police cordon with Mary Jane close behind. Neither they nor the other onlookers can believe their eyes when they see a crimson energy beam extending like a miles-high flame from the building's roof, illuminating the surrounding area with a garish light. Peter senses the evil in the air and rushes off to change into his Spider-Man costume, leaving Mary Jane alone. Annoyed, Mary Jane finds an open door into the museum and enters, hoping to find Peter — who she knows is not cut out to be a hero.
Spider-Man's spider-sense tingles urgently as he stalks through the darkened building, and suddenly he is seized in slimy tentacles and hurled toward a group of grotesque demons. Then, as he tries to battle his way out of their clutches, Mary Jane sees him. Instinctively, she grasps a sword from one of the exhibit cases, and the weapon begins to glow. As she removes it and holds it upraised in her hand, the glow surrounds her, and suddenly she vanishes, to be replaced by the Hyrkanian heroine, Red Sonja. Sonja cuts a swathe through the demons that Spider-Man is battling. Although Spider-Man has no idea who she is, he is more than grateful for the support, and soon the demons fall back. But then a wizened figure, wearing the mystic amulet on its chain around his neck, attacks Sonja with a burst of energy. After a sleep of centuries, rumbles Kulan Gath, they meet again. Spider-Man snags Sonja with a web-strand before the spell can engulf her and carries her up to the ceiling, but she thinks the "human spider" is another of Kulan Gath's demons. Unfortunately, Sonja's language bears no resemblance to English, which prevents them from communicating. She strikes Spider-Man in the head with the hilt of her sword, and they both fall to the floor. The impact knocks them unconscious.
When Spider-Man and Sonja come to, they are bound to a pair of X-shaped crosses in a museum gallery. In the floor below them is a pit, bubbling with viscid liquid. Because Spider-Man is bound like she, Sonja can see her mistake in battling him before. Then Kulan Gath introduces himself, using a spell to make himself understood to both Spider-Man and Sonja. Here, in this Stygian temple, proclaims the sorcerer, the Elder Gods — the N'Garai - will be reborn. The pit is a Sa'arpool, a mystic gateway to the N'Garai home dimension, and as Spider-Man and Sonja watch, the liquid within begins to seethe and a tentacle reaches out toward Sonja. As she curses the magician, he explains that in her last battle centuries ago, in which she cut out his heart, he sent his soul into an amulet to await this very night, when the juxtaposition of occult forces allowed him to ensnare a host body and assume his corporeal form. Spider-Man knows that the amulet and necklace are part of a recent archeological discovery in Europe and predate man's oldest recorded civilizations. This whole wing of the museum was recently remodeled to resemble an ancient Egyptian temple. Spider-Man knows that it is just a stage set, made of paint and plywood, but the wizard seems to think it is real. So Spider-Man snags the ceiling with his webbing and begins to pull. But just then, the liquid bubbles out of the pit and starts to cover Spider-Man's body. Fighting off lethargy, Spider-Man shatters his bonds and web-swings out of reach. Although he feels weak, he manages to pull the plywood props down onto Kulan Gath. Then he leaps toward Red Sonja and frees her. The enraged wizard informs them that there we only three Sa'arpools on Earth, and they have just sealed the second one, perhaps forever. Then with mystic gestures he sends his N'Garai demons after them. Spider-Man carries Sonja out of reach of the demons, but they web-swing up to a mezzanine, they once again come face to face with Kulan Gath. Sonja wants the wizard for herself, but because Spider-Man cannot understand her, he simply does what he thinks best. Dodging Kulan Gath's mystic bolts, Spider-Man smashes him through a window into the street, and Sonja follows. But when Kulan Gath and Sonja see New York City, the crowd of onlookers, and the lights from the news media they are struck speechless. The sorcerer is overwhelmed by how much the world has changed since the Hyborean Age. This allows Spider-Man to deliver a knockout punch. Sonja tells Spider-Man to grab the amulet before the sorcerer can use it once more, but Spider-Man already has the amulet in his hand.
Bereft of the amulet, Kulan Gath vanishes, and in his place the guard, Gus Hovannes, lies on the floor. Spider-Man knew that the sorcerer was occupying an innocent host body, and this is why he hoped to keep Red Sonja from actually killing him. Then, her mission accomplished, Red Sonja fades away as well, leaving Mary Jane to fall unconscious into Spider-Man's arms. When the police rush up the stairs into the building, noting that the crimson energy beam vanished as soon as Spider-Man knocked the sorcerer out, they find only the security guard, who remembers nothing. The events of the evening seem like a dream to Mary Jane. Spider-Man swiftly takes her home, and then, as Peter Parker, he boards the Staten island Ferry and pitches the amulet far away into the Atlantic Ocean. Just before he threw it, it spoke to him and tried to persuade him to put it on, but he was able to resist its temptations. Happy that everything ended well, he thinks of Red Sonja and starts to crave a flagon of ale.