A dark and mysterious horror of cosmic proportions besets a man living in the "house on the borderland" that presides over a bottomless pit. Hodgson successfully builds up the tension and horror throughout the book marred only by a strange interlude in which the pace of the story is brought to a crawl. In order to enjoy this bit you really need to just immerse yourself in the narrative and try hard to visualise and conceptualise all that is being described.
The book picks up pace again for the conclusion and it's horrific finish. What does it all mean, you may be left pondering. Very little is really explained and it is left to the reader to piece it together and (perhaps) draw their own conclusions.
A flawed masterpiece.