Lucio Fulci's thematic trilogy entitled 'The Gates of Hell' is fairly self explanatory. In each film some hapless mortals find themselves dwelling above an entrance to the big H, and wackiness ensues. The Beyond is the second, coming after City of the Living Dead and before The house By the Cemetery.
The film has a simple plot that provides a pretext for a series of horrific set pieces. Some have right compared this film to a fever dream, in that the scenes almost make sense logically, but not quite - they are essentially horrific for their own sake, Yet the film is also visually striking at times in a way not normally found in Eighties horror. There's an art house feel, for instance, when the main character encounters a blind woman and her guide dog on a deserted road bridge.