Explaining what the film is about David Lynch quoted the Aitareya Upanishad: "We are like the spider. We weave our life and then move along in it. We are like the dreamer who dreams and then lives in the dream. This is true for the entire universe."
It's emotionally intense, well made, frightening. A brilliant lead role for Laura Dern, and particularly as there are so few decent lead roles for women. She is not an amazon or a sex-kitten or any female object, she represents the human subject, an 'everyman' figure.
On the negative side, it is three hours long, and there is no coherent plot, though there is a sort of fragmented story. I watched it in half-hour blocks over several days.
The story, such as it is, is that Laura Dern is an ultra-wealthy Hollywood actress, who is cast as the lead in a new film, a bit like Blood Simple, about an affair and a murder. It then transpires that the film is cursed, that it is based on an unfinished German expressionist film whose actors were horribly killed, which was in turn based on a cursed Polish folk story.
It is then unclear whether the film starts to curse her life, whether she is caught up in a real affair and murder involving her husband and her co-star, whether she has a nervous breakdown and thinks the film is true, or whether reality itself is coming apart. Actually this is a bit like Red Shift, but with Hollywood superstars instead of teenagers in Cheshire. She seems to be falling through levels of reality, or parallel lives, each time into greater poverty and degradation. There are also extracts from other films or dreams, some in Polish or Russian. Lynch uses his familiar skill with sound and vision to make the atmosphere foreboding and unheimlich.
There is also a chorus of beautiful slightly trashy ladies who I think represent the forces that sustain and renew the universe: delightful but without pity. There is a sitcom which seems to be set in hell, where all the characters have rabbit masks on. I think this represents the innermost self, and the horror of existence. I do have a feeling about what is happening, and the arc of the story - which I think is redemptive - but your guess is as good as mine.