At the start of this issue, Spider-Man notices a mysterious person breaking into a jewellery store, and so goes in after him. The mysterious person soon attacks Spider-Man, and Spider-Man notes that his webbing doesn't stick to the mysterious person. The person then escapes, all without having said a single word, and so Spider-Man runs after him. However, whilst chasing him, Spider-Man slips on a patch of ice on the ground, which is surprising considering that it's 60 degree weather. Spider-Man decides that the person will be far away by now, and so goes back to what he was doing before he saw the robbery- heading to see Aunt May. When he reaches Aunt May's house, he finds out that Aunt May has the flu. Despite Aunt May assuring Peter that it's nothing, the doctor who is seeing her tells Peter that it's a new type of flu virus, resistant to any types of vaccine that are currently possessed.
The doctor tells Peter that there is a new type of vaccine being brought to America by its discoverer, Dr. A.J. Maxfield, but that Maxfield is eccentric and refuses to fly. Instead, Maxfield is coming by boat, and so may not arrive in America in time to get the vaccine to Aunt May. The doctor tells Peter that nothing can be done to save Aunt May, but Peter has a plan in mind. Peter then changes back to his Spider-Man costume, and heads to the Baxter Building, where he meets up with Johnny Storm. Spider-Man manages to persuade Johnny into lending him a plane to take to the boat which Maxfield is on, and after the automatic pilot is set, Spider-Man gets in the plane and gets ready to leave. Just before going, he tells Johnny that if he wants to, he can check out the jewellery store where he encountered the mysterious thief (this subplot continues into Marvel Team-Up #23).
The plane reaches the boat within fifteen minutes, and is programmed by Spider-Man to hover in an artificially created cloud whilst he finds A.J. Maxfield and convinces him to come on the plane. Knowing that dressing as Spider-Man will only attract unwanted attention, Spider-Man changes to his Peter Parker identity. Meanwhile, at another part of the deck, a bat lands on the deck and transforms into Count Dracula, the lord of the vampires. Dracula thinks to himself that he's looking for A.J. Maxfield, as the vaccine he has discovered may interfere with his plans one day if it's used properly. As Dracula walks along the deck, looking for Maxfield, he coincidentally bumps into Peter Parker. Peter then apologises for running into Dracula (although he doesn't know who it is), and continues looking for Maxfield, just as Dracula is.
On one of the upper decks, some members of the Maggia, led by Anthony "The Whisperer" Cavelli and his lieutenant Seymour "Simian" Simms, are ordered to track down A.J. Maxfield. As there is a costume party on the ship that night, the Maggia members can get away with dressing as guardsmen. Cavelli reminds the Maggia members that they don't just want Maxfield, but the vaccine which he is carrying, so then that way he can trade the vaccine for free passage into America. The Maggia members then all run off to find Maxfield. Meanwhile, Dracula is in need of some blood to drink, and so approaches a young woman dressed as a Viking. As he starts to lure her to the shadows, another man who was about to take a photo of her realises how good Dracula's "costume" is, and so takes a photo of Dracula with a Polaroid camera. However, as the photo comes out, Dracula isn't in the photo due to his magical nature, and when the photographer and the girl look up, Dracula is gone.
Dracula rematerialises on the topmost deck, still looking for someone's blood to drink. Some of the Maggia thugs find him, and think that he could be A.J. Maxfield, as he isn't on the ship's roster, and so try and capture him. Unfortunately for them, their bullets travel straight through Dracula, and so Dracula hypnotises them into walking off of the ship and into the water, drowning themselves. Dracula then finds a lone woman (a different one to the one dressed as the Viking), and hypnotises her so that he can drink her blood. Despite the hypnotism, the girl still screams, which is heard by Peter Parker. By the time he reaches the girl, Dracula has transformed back into a bat, and the girl is nearly dead. A few minutes later, Peter Parker is being questioned by the ship's captain, who thinks that he's a stowaway, whilst he and the captain wait for the ship's doctor to arrive.
The photographer and the girl dressed as a Viking then enter the room, and the captain thanks Doctor Maxfield for answering his call. The photographer is then about to examine the girl, as the captain fears that she's nearly dead, when some of the Maggia members enter the room. They manage to grab Maxfield, but are attacked by the Viking girl for trying to threaten a man of medicine. The Maggia thugs then knock out the girl, and in the confusion Peter Parker escapes through the ship's porthole, and changes to Spider-Man. Knowing that there won't be enough room to maneuver in the tight corridors, Spider-Man uses his webbing to cut off the Maggia thugs' exit paths, forcing them up onto the open deck, where they find Spider-Man. However, when the Maggia thugs prepare to shoot Spider-Man, he starts pleading for them not to shoot, before taking off his mask and revealing that he's a member of the ship's crew dressed up for the costume party.
The real Spider-Man then arrives, and by using his agility and super strength, manages to take out all of the Maggia members. Unfortunately, Maxfield has escaped in the confusion, presumably to get away from the Maggia members. Spider-Man then searches the ship for Maxfield once more. Dracula, meanwhile, is in the ship's ballroom, hoping to find Maxfield there. Dracula notices the Maggia thugs talking to Anthony Cavelli, and realises that the two are connected. Whilst this has been happening, Maxfield has come into the ballroom, panicking because of the Maggia thugs. Cavelli then tricks Maxfield into thinking that he's sick, and leaves with him, planning on kidnapping him once hes out of sight. However, Dracula silently follows the two of them.
As Dracula follows them, Anthony Simms appears, asking Dracula why he's following his boss. Dracula then uses some form of hypnotism on Simms to drive him crazy, and then keeps following Maxfield and Cavelli. Dracula then says that he's there to kill Maxfield, but Cavelli can't have that, and so tries stabbing Dracula. However, Dracula is immune to the blade, and so kills Cavelli by drinking his blood. He then approaches Maxfield, who stammers out that Dracula doesn't understand. Dracula ignores this, and throws Maxfield over the edge of the boat. Satisfied that his work is done, Dracula turns into a bat and flies off. Meanwhile, Spider-Man is looking through portholes in the hopes of finding Maxfield, only to have Maxfield fall on top of him after being thrown over the edge by Dracula. Spider-Man then heads up to the deck with an unconscious Maxfield.
Anthony Simms is still psyching out from what Dracula did to him, and threatening to kill people in the crowd. Spider-Man manages to knock him out, and Maxfield then thanks Spider-Man for having saved him twice in one night. Spider-Man starts to ask Maxfield for his vaccine, but Maxfield then stops him, and tells Spider-Man what he's been trying to tell everyone all night: his name is Hennessy, and he's the ship's doctor- not A.J. Maxfield. Everyone who has been chasing him has simply assumed he was Maxfield, but he never confirmed it. The girl dressed as a Viking then appears, and reveals that she is A.J. Maxfield- whose full name is Alice Joyce Maxfield. Spider-Man then explains his situation to her, and she agrees to take the vaccine to New York with Spider-Man. Shortly afterwards, Spider-Man and Maxfield leave in the plane which Johnny Storm gave Spider-Man at the start of the issue and head for New York.
This issue also reprints Strange Tales Annual #2.