There is probably a story which is told, but with many layers of eta-vision overlaid. Since we are seeing the world from inside the memory of the detective, Fisher, (is there some nominiative determinism between his name and the waterlogged imagination inside him) do is dredging up memories of a traumatic last case under hypnosis, it is difficult to see through the representation to a possible real world beyond.

Has the society collapsed, or does it just seem so. Something has happened but is it inside or out. Did Osborne, Fisher's mentor and solver of the original Harry Grey case which ended in HG's death - allegedly -, did he then go on to complete the next murder himself, and did he recommend his best pupil to investigate the new case knowing that he would fall into the same trap of using his (Fisher's) "method" and complete the first set of murders himself by finding the missing location whilst having used 'the method' to get into HG's mind, and thus feel compelled to close things with a final murder.

Which begs the question would there have been the outline of a 'G' making a further set of murders...