We begin with Fulci shooting a sequence featuring cannibalism and dismemberment via chainsaw, after which they break for lunch. Fulci goes to a nearby restaurant, but the thought of a fillet sickens him, and whatever you do, don't mention the steak tartare! It escalates to Fulci having visions of people being murdered, or faces melting, and other naughty bits (many being taken from other films). The visions become so troublesome that the director goes to a psychiatrist in search of help. Unfortunately, he picks the wrong doctor.
It seems this doctor has some murderous intentions, and sees the good, but ailing, Lucio Fulci as the perfect patsy. The doctor watches all of Fulci's films and reads all the scripts as "research" to help Fulci get to the root of his problem. However, he has the ulterior motive of researching interesting ways to kill people on his rampage and using Fulci's problems of assigning blame away from him and onto the director.
Watching Fulci slowly become consumed by his creation is interesting. The director becoming the victim, so to speak, of his own creations. What is the relationship between a director and his film? Could a lifetime of helming gore films take a toll on one's psyche? In the film it takes an unexpected turn when he suffers from car trouble and arrives late to the set only to find the assistant director has taken over and continued the shoot without him. Can a director become so predictable that he isn't even needed?
After you deal with Fulci's madness from a lifetime of horror, you still have the doctor to deal with. He stands in for the audience, a student of Fulci, based on his consumption of the director's catalog. Rather than horrifying, it is inviting, encouraging imitation. The doctor uses the films as something of a template with which to carry out his own murderous intentions. Is this who is thought to be the audience?
It is interesting to stop and think about how we react to what we consume as entertainment and how it affects us, just as the creator is affected by a lifetime of the same material. It would be naive and arrogant to think it has no affect on us. The key is to recognize it and know how to digest such material. Cat in the Brain takes a look at one possibility.