After several failed attempts to get himself arrested, Soapy spots what looks like an ideal opportunity.
In a cigar store he saw a well-dressed man lighting a cigar at a swinging light. His silk umbrella he had set by the door on entering. Soapy stepped inside, secured the umbrella and sauntered off with it slowly. The man at the cigar light followed hastily.
“My umbrella,” he said, sternly.
“Oh, is it?” sneered Soapy, adding insult to petit larceny. “Well, why don't you call a policeman? I took it. Your umbrella! Why don't you call a cop? There stands one on the corner.”
Soapy would not have taken the umbrella if he hadn't seen the policeman standing on the nearby corner. To Soapy's surprise, it appears that the man who claims to be the owner of the umbrella doesn't want to have anything to do with policemen. He must have stolen the umbrella out of a stand inside some restaurant or bar. All men's umbrellas look pretty much alike. They are always black, and in O. Henry's time women would also carry black umbrellas. This is one of many examples of how Soapy can't get arrested when he wants to. There is one example of how he finally does get arrested when he doesn't want to.
As the title "The Cop and the Anthem" suggests, Soapy has an epiphany at the end when he hears the church anthem and thinks about his former life. He decides to become a new man. He will get a job and climb back into the respectable world he left behind. But ironically a cop approaches him at that inspirational moment:
“What are you doin' here?” asked the officer.
“Nothin',” said Soapy.
“Then come along,” said the policeman.
“Three months on the Island,” said the Magistrate in the Police Court the next morning.
So Soapy gets the three months on Riker's Island he originally wanted—but only after he doesn't want it anymore.