Whilst working on his Spider-Man equipment, Peter Parker is visited by Flash Thompson and Harry Osborn. Upon seeing Flash, Peter attacks him, thinking that he had gone on a date with Gwen Stacy (several issues ago). However, Flash explains that he's completely innocent, and that Gwen had asked him out to talk about Peter. After Peter apologizes to Flash, he calls Gwen up, to apologize for thinking she was cheating on him. Gwen and Peter agree to go to an art exhibit, where Captain George Stacy is guarding many priceless paintings.
Upon getting to the exhibit, Peter and Gwen are about to kiss, when Gwen's father walks past. However, Peter notices that Captain Stacy more or less ignores the two as he walks past to the private room, where the most valuable paintings are. A few minutes later, someone walks into the private room to find most of the paintings missing.
When Gwen and Peter get to Gwen's apartment, they find Captain Stacy there, who claims he hasn't left for the exhibit yet. Although the insist that they saw him at the exhibit, Captain Stacy says he can't remember much of what has happened that day, and concludes that he must have been drugged. This proves to be correct, as the Chameleon had impersonated Captain Stacy so that he could steal the paintings.
As Peter tries to work out what happened, he comes to the conclusion that it must have been the Chameleon who impersonated Captain Stacy, as no one else could have done so so skillfully. Knowing that he might never find the Chameleon, Peter changes to his Spider-Man identity goes to the Daily Bugle. There, he asks Robbie Robertson to put a piece in the Daily Bugle talking up a transfer involving one million dollars.
The next day, as Peter Parker, Peter is taking pictures of the transfer. His spider sense tells him that the Chameleon is somewhere in the crowd, but he can't tell who he is exactly. Spider-Man goes into the private room where the transfer is being negotiated, and again he can tell that the Chameleon has disguised himself as someone, although he can't tell who. The people in the room notice Spider-Man, and he is forced to flee, since they think he wants to steal the money himself. Spidey then goes to wait outside the building to see if he can catch the Chameleon when he leaves.
Coincidentally, when the Chameleon comes out, he is disguised as Peter Parker, whom Spider-Man knows he can't be. He then manages to stop him getting away, and unmasks him as the Chameleon.