Peter arrives home to catch the news broadcast about the alien organic mud that was brought back on the space shuttle commanded by Colonel John Jameson. It has been taken to the university where Dr. Connors is conducting research. Peter calls Brock, who warns that Martha Connors doesn't want Peter there since she can't trust him. Peter goes there as Spider-Man and uses his zoom lens to take photos, then heads for the skylight to get inside. He sees a woman dressed in black slip in ahead of him past the security systems. She heads for the containment device holding the alien ooze and Spider-Man intervenes. She introduces herself as Black Cat and then the two end up sparring. She notes that a certain captain of industry is paying her to steal the material and offers him a partnership but he turns her down. However, when Dr. Connors comes in the Black Cat takes advantage of the distraction to escape with the alien substance.
Spider-Man makes his escape but the Bugle runs a story that Spider-Man stole the alien substance. Brock is upset, since Peter sold his pictures of the fight to the Bugle and didn't call the police. Peter confronts Jameson about portraying Spider-Man as the thief, but Jonah notes that it's standard crook practice, and Connors claimed the alien substance wasn't stolen until the next morning. Peter is confused since this contradicts his meeting with Connors right after the theft.
"Dr. Connors" is reading about the newspaper and chuckling over Spider-Man's confusion, then unmasks himself to reveal that he is the Chameleon. He reports to his employer, noting that Black Cat just beat them to the lab. The Chameleon then has his two henchmen, Mason and Beck, prepare to use their mechanical and special effects expertise, respectively.
Spider-Man is on patrol, unaware that a bit of the alien substance has attached itself to him and created a new black costume. The Black Cat confronts him and claims that she was framed as well and wants his help to clear her name. She also compliments him on his new costume, which he finally notices. He refuses to team up with her and swings away, and notices a plane crashing in midtown. He leaps on board, making a leap beyond his normal capabilities, and manages to escape with the pilot just in time. He also saves two construction workers from falling beams and realizes that the ooze is enhancing his abilities. He figures it might be better not to return the ooze then goes home where he discovers the alien costume can respond to his thoughts. He comes in to find Aunt May stressed from cooking, and gets her to bed.
At the downtown bank, someone wearing the original Spider-Man costume robs the bank and escapes. Peter arrives at school to discover that Flash is defending Spider-Man despite his recent involvement in robberies.
"Spider-Man" robs a bank but it's clear he's using mechanical devices and uses his hidden confederates Mason and Beck to help him and take photos to give to the Bugle anonymously. Jonah is happy that the Spider-Man has been shown up as a criminal but Peter goes to look for the imposter and runs into the Black Cat. She offers her help and leads him to an ocean liner hosting Mayor Water's party, figuring the thief will strike there. She's particularly interested in the mayor's cats' head necklace Captain Stacy has his men on high alert and Jameson is at the party as well. They're unaware that Mason and Beck have infiltrated the ship in disguise.
Norman Osborn is also there with a political contribution for the Mayor but he's the Chameleon in disguise. Black Cat gets Spider-Man on board using a jet ski, and he finds an unconscious policeman. The Mayor calls a toast when the Chameleon makes his entrance as "Spider-Man" and readily defeats Captain Stacy, while the policemen drop unconscious thanks to Beck giving them drugged coffee. Stacy realizes the Chameleon is a fraud but the Chameleon takes him out. The real Spider-Man arrives and takes on the Chameleon, defeating him. Beck provides a diversion and he and Chameleon escape outside and meet up with Mason, who uses a drone device to hold Spider-Man off. The Black Cat takes out Mason and Beck while Spider-Man webs onto the Chameleon's escape boat and water skis after him. The Chameleon tries to shake him without success and the Spider-Man gets onboard. The Chameleon uses electro-gauntlets to boost his strength but the hero still defeats him as Black Cat looks on.
Jameson reluctantly orders a retraction (on page 42) while Stacy apologizes to Spider-Man. He promises to find the alien substance and Spider-Man lies so he can keep the suit. The Chameleon manages to slip away with the Mayor's necklace. Later, Spider-Man finds Black Cat and wonders why she helped him, and she kisses him while secretly considering the cat necklace she took from the Mayor. Black Cat then slips away, leaving Spider-Man to wonder.