The mood of “After Twenty Years” is simultaneously light-hearted and mysterious. The light-hearted nature of the story comes across in the ironic ending (as “Jimmy” turns out to be a plainclothes police officer and an on-duty police officer turns out to be Jimmy) as well as in Bob’s conversational and meandering descriptions of his friendship with Jimmy.
The mysterious mood comes across in the short moments when the narrator interrupts the long swaths of dialogue to capture the setting, as seen in the following passage:
There was now a fine, cold drizzle falling, and the wind had risen from its uncertain puffs into a steady blow. The few foot passengers astir in that quarter hurried dismally and silently along with coat collars turned high and pocketed hands. And in the door of the hardware store the man who had come a thousand miles to fill an appointment, uncertain almost to absurdity, with the friend of his youth, smoked his cigar and waited.
Here the narrator describes the “fine, cold drizzle” and the “uncertain puffs” of wind that became “a steady blow.” They also note how the “few” people walking nearby were “astir,” “dismal,” and “silent” with “coat collars turned high.” All of these descriptions encourage readers to sense that there is a dreary and unsettling energy over the scene. Likewise, the image of this unnamed man who “had come a thousand miles” for an “uncertain” meeting with an old friend, “smok[ing] his cigar and wait[ing],” adds to the mysterious mood. At this point, readers want to know more about the man and what will happen if and when his friend finally appears, likely sensing that it will not be a straightforward affair.