Well, I don't want to give too much of the plot away, but the Fearmonger is a creature that feeds off emotions, specifically fear. It inhabits a human host and uses that host to influence those around it. It creates situations where people feel frightened - hence its interest in Harper and her New Britannia party. The production standards are great. When there is music it is used to good effect.
Sound effects paint a picture without ever overdoing it.
The cast were all enjoyable. The story is divided into four episodes which works well, but also leads to my only serious complaint on an otherwise excellent product. If you stop at the end of an episode then you don't know which track to go back to next time. There's nothing anywhere on the case or the enclosed booklet to tell you that episode 2 starts on disc 1 track 7 and episode 4 starts on disc 2 track 6. There's a batch of audio trailers on the end of the second disc.