John Trent (Sam Neill), a private investigator, is hired by an editor to find Sutter Cane, an author of horror stories who has disappeared along with his most recent manuscript. The search leads him to Hobb's End, a mysterious place where strange things are happening. Trent becomes the main character of Cane's novel and of the film which is based on it.

John Carpenter’s Apocalypse Trilogy of films (The Thing, Prince of Darkness, In the Mouth of Madness) do not share characters or locations, but they are connected in their nihilistic view of a vast and uncaring cosmos, where unknown terrors dwell.
“All three of those movies are, in one way or another, about the end of things, about the end of everything, the world we know, but in different ways.” - John Carpenter