WMG: In the Mouth of Madness

Sutter Cane didn't actually write the events of the movie.
While John Trent goes off the deep end after discovering that he is a fictional character written by Sutter Cane, he is only half right, and the truth is far worse: Sutter Cane is also a fictional character, written by an Eldritch Abomination to write the gateway into our world for its kind. This means that John Trent is a fiction written by a fiction, and his whole world is even less real than he thinks he's discovered.