Hmm.. based on the title... [touching forehead] I'm guessing an invisible man plot for this episode.
Dr. Vespasian is hard at work in his laboratory. When he finishes his latest serum, he adds some milk [Seriously that's what's printed on the carton] to make it more palatable to his test subject: his dog Brutus. [Wait. Feeding a dog milk? Won't the cat unions get in an uproar? The dog looks like Scooby Doo with a spiked collar. What gives?] Seconds after the dog finishes the bowl, he vanishes leaving no trace except for his collar.
Vespasian jumps for joy that his chemical "Invisocine" works correctly turning flesh transparent. He then chugs down a large glass of grape-flavored invisocine and becomes invisible as well. He uses his invisibility with his other projects specifically designed to assist him rob banks: high-powered lasers to melt the locks and a "money magnet" which is nothing more than a giant vacuum pump he uses against lose cash.
After a series of successful heists, the mayor calls in Spider-Man to assist him. They are unware of how the thefts are occurring. Spider-Man promises to do what he can.
Vespasian turns the tables on his financial backers and elects himself the new crime boss of the group. Their first target: Spider-Man. They set a trap for him at a bank, leaving him trapped in the vault with Brutus the invisi-dog. Somehow he gets covered in a fine powder which takes away his advantage. Spider-Man traps him in a canister until animal control can be contacted. [I assume. It's never mentioned.]
The next day Vespasian decides to go after the crown jewels of Ranchipur currently under heavy guard at the Third Tibetan Bank. Spider-Man knows that the jewels will be Vespasian's next target. He meets with the mayor to arrange for a special surprise that involves and ice cream truck and the bank vault. [Now I am scared.]
That night Vespasian decides to wear red gloves during this theft, which completely cancel the whole "invisible" aspect. He sneaks into the bank, knocks out the guards, and enters the vault. Spider-Man easily picks him out due to the red gloves and moving drawers. Not content with just keeping him trapped in the vault, Spider-Man had arranged to have a giant dispenser installed over the deposit boxes. He begins coating Vespasian in various flavors of ice cream, turning him into a sundae. Complete with sprinkles. [I wish I was kidding.]
The police capture the rest of the gang and take all of them to jail.
They actually made a character so goofy looking that Dr. Doom would give him the mask off his own face and tell him, "You need this worse than I do". It's no wonder they made him invisible. To one-up this element, they have Brutus the invisible dog. It's almost a good idea.
I know that animating things on a limited budget is difficult. But when you have two invisible characters in one episode, something's wrong.
Naming the invisibility formula "invisocine" is also a close approximation to a good idea. It sounds good, but the more you say it, the less you like it.
1/2 web. Two invisible characters, a giant money vacuum, and a resolution that involves turning the villain into a giant sundae. If I had written this episode, I would turn in my writer's union card.