Griffin continues his story. Oh, when will it end?
Griffin was getting more and more upset about the whole invisible situation.
He made his way to a costume shop to find wigs, noses, and other stuff, so that he might appear "a grotesque but still a credible figure" (23.8).
When Griffin found his way to a store, the very alert shop owner almost caught him. The shop owner had a revolver, and he kept locking doors behind him.
This made Griffin angry, which seems to be his only emotion. So he knocked out the shop owner and tied him up. (And that's the last we hear of that guy. Kind of sad for him.)
Kemp interrupts Griffin's story to tell him that he isn't following "[t]he common conventions of humanity" when he knocks people out in their own homes (23.23). Griffin points out, though, that he's not a common person.
Back to the story: Griffin went ahead and stole money and clothes. At least now people will be able to see him.
Griffin stops his story for a minute in order to give Kemp a long speech about how being invisible isn't so great. For one thing, he can't eat in public because he can't reveal his mouth. (This explains why he never ate in front of people at the Coach and Horses in the earlier chapters.)
Kemp wants to keep him talking, so he asks what happened after he got all dressed up.
Griffin continues his story:
He got his books and ordered the equipment he would need. All he wanted was to figure out how to reverse the invisibility treatment. Unfortunately, those gossipy people of Iping interfered with this plan. He asks, "Why couldn't they leave me alone?" (23.56).
Now that everyone has gotten in his way – especially Marvel – Griffin is even angrier than before and plans on killing people. We would be worried about that, but when was the last time one of Griffin's plans went well?