The Batman swoops in, too late to save the man but in time to save a little girl who was also in the room. The cops break in as well and seem to be every bit as interested in ventilating Batman as they are capturing the Joker. It appears there's some sort of conflict on this point between Commissioner Gordon and the mayor.
Gordon's already using the Bat-Signal, which seems ridiculously low-tech in this era of disposable cellphones and holographic concealment of the Bat-Cave. We learn that the girl's name is Olivia Carr, and the victim of the Joker's frenzy was her uncle.
She overheard the Joker mention his hiding place, and Batman is off, but arrives after the cops have already burst in on a dummy. A bomb inside kills all the police and stuns Batman, but he recovers in time to catch the Joker on a subway train. The Joker is imprisoned at Arkham. End of story?
Not quite. The Joker has a visitor. It's the father of the man he killed, who is apparently called the Dollmaker. They appear to be in some plot together, and he cuts off the Joker's face.
To be continued....
Sorry, folks but that's quite enough for me.
Update: Re-reading this, one thing strikes me. When I am describing one of the Golden Age or Silver Age 8-page stories, I would have to spend more paragraphs describing the plot than I did for this tale. I would be very surprised if the word count per page here is more than 1/2 that of a typical Silver Age book.