In the Mouth of Madness is John Carpenter's homage to H.P. Lovecraft and is the last of his "apocalyptic" trilogy. We grow more impressed with this film with each viewing: Not only does Carpenter take on the challenge of filming the unfilmable, he succeeds in ways that few, if any, other directors have.
We first see John Trent, played by Sam Neill, incarcerated in a psychiatric institution. The story works backward from there. Trent is an insurance claims investigator who has been assigned to investigate the disappearance of the author Sutter Cane. Even as he is informed of the assignment, an ax-wielding man smashes through the window and asks, "Do you read Sutter Cane?" before raising his weapon for a swing.
Cane's latest novel is called In the Mouth of Madness, and riots are breaking out at bookstores where it is sold. A followup has been completed, but it is missing. His agent has the only existing fragment, but he can't talk about it, because the police killed him when he swung his ax at Trent. The agent's behavior is not unusual, as Cane's books produce disorientation, memory loss and paranoia in their readers. But his novels sell, and the pressing issue for the publishing company is that the next book's film rights have been sold in advance. They need that book, and they hire Trent to find it.
Trent cares little for the horror genre, and he doesn't seem to like much of anything at all. His fraud investigation work routinely brings him into contact with the worst in human nature. Whether his work poisoned his attitude or he chose his profession because he already was that way, he is cynical and believes that anyone is capable of anything at any time. This pessimism plays into the movie's apocalyptic plot, as he feels that the human race has messed up the planet, so we might as well throw our brains into the toilet, too.
Trent gets some of Cane's books to get a feel for the man's mind and to look for clues about where he might be hiding. He is immediately accosted by strangers who tell him, "He sees you," and he has visions of ax-wielding mobs and monstrous, brutal policemen. Despite these disturbing and highly realistic hallucinations, he is able to piece together the location of Hobb's End, the fictional setting of Cane's novels. Trent is convinced that the place, although it appears on no map and is absent from the state's history and records, is real and that Cane is there.
Editor Linda Styles accompanies Trent to search for the presumably mythical location. A strange car ride, part of which leads them through midair, takes them to Hobb's End. They find the local hotel to be exactly as the one described in Cane's books, but the woman who runs the place has never heard of him. Both of the travelers experience strange reality distortions, and as they grow more severe, Linda becomes convinced that Cane's work is not fictional.
This weirdness seems to center on a local church. When they investigate it, violence breaks out. Linda is particularly alarmed at the idea that Cane's work might be true, as she knows that his latest book is about the end of the world. She finds him inside the evil church, writing. He claims that what he thought was fiction has in fact been dictated to him by the beings that live beyond...that buckling door right there. When he opens a door to some other reality, things get much weirder. Which is saying a lot, because this film left "conventional" in the rear view mirror sometime around the opening credits. The movie is about reality, and alternate realities, and it explores the idea that the reality is created in the mind of the writer and reader. And the viewer.
Numerous Lovecraftian elements are worked into the story. One of Cain's books is called The Whisperer in the Dark, a reference to Lovecraft's "The Whisperer in Darkness." A bookstore display depicts a being that looks like Cthulhu, a deity in Lovecraft's pantheon. The setting in a fictional New England town is common in the work of Lovecraft, who based his settings on real places but gave them names like "Innsmouth" and "Dunwich." Trent stays at the Pickman Hotel, Pickman being a surname with special significance in Lovecraft's stories. An odd chord sounds when a portal is opened to an abyss, a subtle reference to "The Music of Erich Zann."
The Lovecraftian element goes a lot deeper than a collection of sly references, however. There are a number of beings inspired by Lovecraft's universe, and here Carpenter pulled off the trick of filming the indescribable. Lovecraft typically did not describe the beings in his works so much as he gave impressions of them. This engages the reader's imagination and means that, rather than being tied to a specific description that may not be equally frightening to all readers, the reader may fill in the blanks with whatever they find most terrifying. Creatures appear here, but rather than present them as standard monsters, Carpenter shows them obscured by shadows and in extreme close-up. It's never quite clear exactly what we're being shown. It has been said that Carpenter achieved this with The Thing, but this may be an even better example. Not that it's a better movie, overall, although it's very good.
Distorted reality is another frequent feature of Lovecraft's stories, and this is presented in a number of clever ways. The premise that the characters are aware that they exist in a book that is being written in real time could easily be clichéd, but here it is taken a couple of steps beyond the usual. When Cane escapes through a hole he tears in reality, its jagged edges are seen to be the book's pages. Cane then pops in and out, orchestrating Trent's experience like a Freddy Kruger of the waking world.
The story begins toward the end and then works backward, as mentioned earlier. That's fairly common, but what's unusual here is the number of times that the plot moves in circles. Trent frequently relives past events or finds that separate series of events bring him back to the same point. The result is a disorienting feel that suggests the breaks in reality suffered by Lovecraft protagonists who are confronted with things beyond what the mind can process.
A couple of other sneaky references exist: There is a Dr. Saperstein, as in Rosemary's Baby, and the town name "Hobbs End" is the name of the pivotal location of Quatermass and the Pit. One other intriguing potential connection is present, as Cane's latest book concerns an evil that has taken the town's children and is now spreading to the adults. Carpenter directed his Village of the Damned remake the next year. If he thought that the children are our future, he apparently was not excited about what that future might bring.