An architect is arrested for defacing a nearby building because it was built differently than how he designed it, and the detectives soon learn he placed bombs in it as a form of protest. As Harris tries to leave for his vacation in Wyoming, the detectives get held hostage by a pair of gunmen who are looking for a friend who was arrested earlier in the day.

When a thick fog envelopes the city, it causes a burglar to accidentally break into a Christian Science Reading Room by mistake. Barney and the men of the twelfth precinct wait to hear if he gets his promotion to deputy inspector. Levitt brings in a street musician for disorderly conduct and disturbing the peace.