What is the fine-grained topic of the following text: One of the real strengths of this show is its plotting, which uses real concerns and events of the period as the basis for its stories: a factory owner hires the detectives to root out communist agitators, bootleggers' fights spill over into other people's lives, the missing Princess Anastasia turns up (or does she? Only return the topic.
Plot development in a historical period-based TV show