The most common form of the human monster is the mad scientist, as depicted by characters such as Elsa in Splice or Dr. Pretorius in The Bride of Frankenstein, as well as Dr.
Throughout the movie, the idea of what is normal begins to change, and with it the identity of the monster and the nature of the reality its presence challenges. The viewer’s idea of what distinguishes normality, the anomaly, and the monster is constantly challenged as the narrative progresses. Instead of one monster, the film suggests that anyone could be a monster under the right circumstances, and ultimately leaves the viewer to question who is really the monster. Cane himself is by his very nature a human monster. It is through his books that the abjection between fiction and reality is created. In the context of the film, Cane is the original monster, and possibly the most powerful, though it is suggested that even he may not have complete control over everything.
He disrupts what is seen as real by exposing the real world to be a work of fiction; all created from his imagination. At one point Cane even displays a literally monstrous side with a growth on his back—a cue to the audience of his role in the story. Cane disrupts and challenges the normal ideas of reality by revealing the world to be nothing more than an illusion. The characters who read his book In the Mouth of Madness—his agent, Trent’s partner Linda Styles (Julie Carmen), and eventually Trent himself, all find their ideas of what is normal challenged, and in the process become monsters themselves.
Cane might not be the only monster, but he is the driving force behind the film. The other monsters to appear are extensions of his character. With the possible exception of the unseen “Old Ones” that Cane says inspired his writing; even the few instances of literal monsters are constructs of his mind and therefore extensions of his character. This idea is set up early on, when Trent and Styles arrive at the Pickman Hotel, and Styles comments on how the greenhouse is empty but used to be “filled with strange growing things”, and how one night the townspeople saw something moving inside.
Trent immediately recognizes her description as being from the plot of Cane’s novel The Hobbs End Horror (itself a reference to Lovecraft's story The Dunwich Horror). Later, Trent encounters this monster in the form of Mrs. Pickman (Frances Bay), who experiences a grotesque transformation and is seen in the greenhouse. At first, this sub-plot does not seem to contribute directly to the overall narrative, but it marks the point in the story where Trent, Styles, and many of the supporting cast begin to show their status as monsters.
One of the few scenes to clearly show literal monsters occurs when Cane finishes his book. The scene begins with Cane showing that he is capable of warping reality when Trent suddenly finds himself in the former’s writing room. Cane finishes typing the book and declares it “all done” before entrusting Trent to return it to the world. Cane explains that “you are what I write” and states that nothing within this world existed before the story began. Cane continues to emphasize the idea of the world being fiction when he embeds his fingers in his face and tears it apart like a sheet of paper, exposing a black, empty void. The camera looks back at Trent from inside the void. From this side, the door that was behind Cane is replaced by a page from a book. Though the hole prevents the page from being read clearly, the text that is visible refers to Hobb’s End, suggesting that the viewer is literally looking into a page from one of Cane’s books. As Trent approaches the hole, Styles begins reading part of the manuscript, which describes in detail precisely what is happening.
The presence of Cane as the writer allows the film to further create this disruption through the use of abjection, an idea proposed by Julia Kristeva which suggests that horror resides in the middle of established social boundaries such as the living and the dead, human and animal, and male and female, or in this case between reality and fiction. The horror of In The Mouth of Madness comes not from Cane himself or from the Lovecraftian "Old Ones" he claims have influenced his work, but from the idea that everyone within this world, including Trent, is a fictional construct whose every action is dictated by the author and who only exist to serve the needs of the story.
Moments of abjection between reality and fiction recur throughout the film, beginning with Trent and Styles encountering a town that should not exist—later in the film it vanishes entirely, along with Styles who was literally written out of existence by Cane. The confusion is further emphasized when Trent finds himself reading one of Cane’s books while exploring the town, and comments that “I’m reading this thing like it’s a guidebook.” This idea of the abjection between reality and fiction reaches its peak in the film’s final moments. Trent sits down in a movie theater with popcorn and watches the film adaptation of the Sutter Cane story In the Mouth of Madness. A brief montage reveals that the film adaptation of the book is literally the film the audience has just finished watching. Reality as the viewer understands it is being disrupted by the idea that their reality is fiction. Trent constantly finds himself trying to rationalize his encounters, but upon seeing himself in his own movie, he is forced to finally realize the truth that none of his world is real.
This idea of monstering goes further. While Cane can be seen as the monster, the film also plays with Carroll’s idea of the anomaly to turn the rest of the cast into monsters themselves. Trent sets this idea up early in the film when he describes the experience of reading Cane’s books. “Pulp horror fiction, they all seem to have the same plot,” he says. “Slimey things in the dark. People go mad. They turn into monsters.” This is precisely what happens later in the film. Cane himself is an anomaly in In the Mouth of Madness, but in keeping with Wood’s ideas of what defines the monster, the anomaly shifts over the course of the film.
In a conversation between Trent and Styles, the latter justifies her love for Cane’s writing by suggesting that “Right now reality shares your point of view. What frightens me is what would happen if reality shared Cane’s point of view”. She goes on to suggest that “sane and insane could easily switch places if the insane were to become the majority”. This discussion sums up Wood’s idea of the monster challenging "normality", a term he uses in a loose sense meaning simply “conformity to the dominant social norms.”
Normality changes over the course of the film, initially with the characters believing that what they are experiencing is reality until Sutter Cane exposes them to the repressed truth. As the narrative progresses, more people become aware and are infected by it in ways that a man like Trent would view as insane. This challenging of Trent’s understanding of sanity is first experienced when he is faced by a man he later describes as a “lunatic with an ax”. The man in question steps out of a bookshop, crosses the street in broad daylight holding an ax, walks toward the diner where Trent is eating with his employer, smashes the glass and then asks Trent “do you read Sutter Cane.” This man is killed by the police, and naturally his actions are dismissed as being the product of mental illness.
Freud’s original concept of “madness” was that it was connected to a person’s own past, but in In the Mouth of Madness it is suggested that insanity is simply a label for any behavior that violates what the majority of the population see as normal. Trent’s own sanity is brought into question, ironically, by his very efforts to rationalize his experiences while everyone around him is turning into what he would consider monsters. This development in Trent’s character ties back to Styles’ comment earlier in the film: that which the viewer would consider insane has started to become the majority, and a character like Trent whom the viewer might ordinarily view as sane appears to be insane by the sheer nature of failing to conform to what has become normal.
The idea that Cane transforms people into monsters is explored more literally through the character of Styles. From her introduction, Styles is a horror fan who attempts to address Carrol’s very question of why viewers are attracted to horror films, as raised by Trent. As a Sutter Cane reader, she finds herself more open to the possibility that his books are real, an idea she begins to develop soon after entering Hobb’s End. When they first arrive at the hotel from Cane’s book The Hobb’s End Horror, Styles displays an uncanny ability to point out minor details about it without looking. She is also the second character to have her reality challenged, after Cane’s agent, when she is forced to read In the Mouth of Madness.
After this scene, Styles becomes a more explicit puppet of Cane’s, having sex with him oblivious to a monstrous outgrowth on his back, experiencing peculiar transformations, and displaying abrupt shifts in personality. With no build up she begins attempting to seduce Trent, much to his shock and confusion. She has herself become a monster, challenging what Trent would see as normal. Styles behaves in ways that he would deem insane, such as swallowing the keys to Trent’s car. She even briefly becomes a literal monster when her body is shown contorting into a quadruped form, walking on both her hands and feet with the sounds of bones cracking heard as she moves.
In the Mouth of Madness is one large distortion of the theories presented by Wood and Carroll. It plays on the idea of the monster disrupting what is normal and challenging the viewer’s understanding of reality by forcing the viewer to question their ideas of reality and what is normal. By leaving the viewer unsure of what they can call normal, the film also brings into question precisely what it means to be a monster or an anomaly. In the end, Cane can be seen as a monster, but he is also a tool used by the filmmakers to explore the question of just what makes someone a monster, and it is through him that the ideas of Wood and Carroll are tested.