In The Mouth of Madness - Plot

Plot

Dr. Wrenn (David Warner) visits John Trent (Sam Neill), a patient in a psychiatric hospital, and asks Trent to recount his story:

After exposing an arson-fraud scam, Trent, an insurance investigator, has lunch with a colleague who preps him on his next assignment, investigating a claim made by New York-based Arcane Publishing. During their conversation, Trent is attacked by a man wielding an axe who asks him, "Do you read Sutter Cane?" The man is shot dead by a police officer before he can harm Trent.

Trent later meets with Arcane Publishing director Jackson Harglow (Charlton Heston) who tasks him with investigating the disappearance of popular horror novelist Sutter Cane (Jürgen Prochnow). Cane vanished days before his latest book was released, and Harglow requests that Trent recover the manuscript for Cane's final novel of his popular series. He assigns Cane's editor, Linda Styles (Julie Carmen), to accompany him—Cane's agent will be of no help as he was the man with the axe who tried to kill Trent earlier.

After reading several of Cane's novels for research, Trent experiences vivid nightmares of monsters and deformed people murdering each other with axes. Linda explains the stories are known to cause disorientation, memory loss, and paranoia in "less stable readers." Trent remains skeptical, convinced that the disappearance is merely an elaborate publicity stunt. Trent notices a series of red lines on Cane's book's covers that, when aligned properly, form the outline of New Hampshire and mark a location alluded to be Hobb's End, the fictional setting for many of Cane's works.

As they set out to find the town, Linda experiences bizarre phenomena during the late-night drive: a boy riding a bicycle whose visage changes as she somehow passes him three times, the yellow road lines vanishing followed by the road itself disappearing, the car driving above thunderhead storm clouds, entering a rustic covered bridge in darkness and inexplicably arriving on the other side at Hobb's End in daylight. Trent and Linda search the small town and begin encountering fictional people and landmarks described in Cane's novel, including Mrs. Pickman (Frances Bay), whose hotel they check into, and the Black Church, described in Cane's books as a fount of evil that pollutes the entire town. Trent and Linda watch as a group of townspeople arrive at the Black Church wielding shotguns and torches, demanding Cane return a missing child. Johnny, the son of one of men of the group, suddenly appears in the doorway to the Church, supplanted by Cane himself. The townspeople are then set upon by dogs and driven off. Trent believes the events to be staged, but Linda does not. She admits to Trent that Arcane Publishing's claim was indeed a fraud and a stunt to promote Cane's book. However, the unusual events and exact replica of Hobb's End were never part of the plan.

Trent prepares to go back to report to Harglow, but is prevented when Linda steals the car keys. She heads to the Black Church to confront Cane, and is exposed to his final novel, In The Mouth Of Madness, driving her insane. Trent is approached at a bar by Johnny's father who warns him to leave before the evil infects him as it has the inhabitants of Hobb's End. Trent later returns to the bar and witnesses the man commit suicide with a shotgun as he proclaims to merely be a character written to do it. Outside the bar, a mob of mutated, monstrous-looking townspeople descend upon him with shotguns and torches. He flees to the hotel and discovers that Mrs. Pickman (who had been tormenting her husband and finally killed him) and Linda have also been altered into mutated versions of their former selves. Trent attempts to drive away from Hobb's End but is repeatedly teleported back to the center of town, subsequently crashing while swerving to avoid hitting Linda. He awakens in a confessional where Cane explains that the popularity of his eldritch stories have created a sufficient amount of belief to free an ancient race of monstrous beings that will reclaim the Earth. Cane further reveals that Trent himself is merely a character and has no choice but to return the manuscript of In The Mouth Of Madness to Arcane Publishing, ushering the end of humanity.

After giving Trent the manuscript, Cane tears his face open like a piece of paper, ripping a hole that leads into darkness and creating a portal to the dimension of Cane's monstrous masters. Trent flees down a long tunnel as monsters chase him and he suddenly finds himself lying on a country road, apparently back in reality. During his return to New York, Trent destroys the manuscript, but it somehow is redelivered to him, prompting Trent to destroy it again and again. Back at Arcane Publishing, Trent relates his experience to Harglow and explains why he has no manuscript to return. Harglow informs him that Linda never existed; Trent was sent alone to find Cane. What is more, Trent himself had delivered the manuscript to Harglow months ago. In The Mouth Of Madness has been on sale for weeks with a movie adaptation set to release soon. Trent suffers a psychotic break and is arrested after he murders a reader of the newly released novel with an axe, asking him "Do you like the book?"

Dr. Wrenn, after listening to Trent recount his story, concludes that Trent's story answers nothing and leaves. That night, amidst a thunderstorm, Trent sees disturbing shadows flicker on the wall and hears human and inhuman screams echo throughout the hospital.

Trent wakes the following day to find his cell door torn from its hinges and the residents of the hospital slaughtered. He departs as an abandoned ambulance's radio announces that the world has been overrun with mutant creatures and outbreaks of suicide and mass murder. Trent goes to see the In the Mouth of Madness metafilm only to discover that he is the 'star' of the film. As he watches his previous actions play out on screen, Trent bursts into hysterical laughter/crying, leaving the exact nature of reality uncertain.