O. Henry critic Boris Ejxenbaum wrote that the O. Henry short story “gravitates toward maximal unexpectedness of a finale concentrating around itself all that has preceded.” This method is certainly evident in "After Twenty Years" as a policeman walks his beat and happens upon a man standing in an empty doorway.
In order to light his cigar, the man strikes a match, revealing a square-jawed face with a think scar on the eyebrow. He assures the policeman that he means no harm; he is simply waiting for an old friend whom he promised he would meet at 'Big Joe Brady's' restaurant after twenty years have passed. He and Jimmy Wells, his best "chum" agreed to meet no matter what the conditions might be or from what distance they had to come. When the policeman queries if the friend has heard from Jimmy, the man replies that he did for a while, but after he went West they lost contact with one another. However, Jimmy is the "truest, staunchest, old chap in the world. He'll never forget."
The man waiting looks at a diamond studded watch. "Three minutes to ten.....It was exactly ten o'clock when we parted." The policeman asks if he will "call time on him sharp." No, replies the waiting man. "I'll give him a half an hour at least. If Jimmy is alive on earth, he'll be here by that time." The policeman bids him goodbye.
After nearly twenty minutes a man with an overcoat collar turned up walks directly to the waiting man, asking "Is that you Bob?" And the waiting man returns, "Is that you Jimmy Wells?" Commiserating upon what a long time twenty years has been, the waiting man remarks that Jimmy is taller than he remembers. As they pass a drugstore on a corner brillant with electric lamps, Bob stops suddenly, realizing the man with him is not Jimmy Wells:
"Twenty years is a long time, but not long enough to change a man's nose from a roman to a pug."
"It sometimes changes a good man into a bad one," replies the tall man, who continues, "You've been under arrest for ten minutes 'Silky Bob.'"
Before the tall man escorts Silky Bob to the police station, he hands Bob a note from Patrolman Wells. In O. Henry's typical ironic reversal, this note informs Bob that he was there at the appointed time, but when he struck the match, Wells recognized the man wanted in Chicago. But, because he did not have the heart to arrest his old friend, he went to the police department and asked a plain clothesman to do the job.