I've referred to In the Mouth of Madness as the best H.P. Lovecraft film that isn't an H.P. Lovecraft film. Here's why. Madness isn't based on a specific work by Lovecraft, so it's not technically a Lovecraft film. But the basic plot hinges on one of Lovecraft's concepts, that ancient beings called The Old Ones once held dominion over the earth and were somehow banished to the outer dark, and they've been trying to get back into our dimension ever since. Not that Lovecraft used this idea as many times as people think. It's mostly a stereotypical plot that pops up in pastiches of Lovecraft's work by other hands. (Including mine.)
In the movie, the path the old ones are seeking to follow is one of human imagination and belief. Sutter Cane, an insanely popular writer of horror novels is the key. To tell you more would reveal too much of the plot, but basically Cane has vanished, taking his last manuscript with him and his publisher hires insurance investigator John Trent (Sam Neill) to find Cane and secure the manuscript if possible. Trent begins reading Cane's books, looking for clues, and is soon embroiled in the stuff of nightmares as he seeks out the creepy New England town of Hobbs End.
I saw this film at the theater back in 1995 with my pals Chris and Lanny. Lanny's wife was so disturbed by the movie that she had to go out in the lobby for a bit. Watching the film again last night I could see how it could disturb someone, especially in the second half. Director John Carpenter knows what scares people. He also knows his Lovecraft, and to some degree, his Stephen King. The title of the film is the first clue as it seems to be a take on Lovecraft's At the Mountains of Madness. The creepy old lady who runs the bed and breakfast where Trent stays in Hobbs End is named Mrs. Pickman, presumably after the artist Pickman from Lovecraft's story, Pickman's Model. There are quite a few gibbering and slavering things from the outer dark in the movie and their pursuit of Trent reminds me of the frenzied escape attempt of the protagonist of Lovecraft's The Shadow Over Innsmouth. One of Sutter Cane's novels is called The Hobbs End Horror, a similar title to Lovecraft's The Dunwich Horror. I've already talked about the basic plot similarities to Lovecraft.
Stephen King is actually mentioned in the film and of course Sutter Cane sounds a lot like Stephen King. Plus, the town of Hobbs End seems more like one of King's New England towns like Jerusalem's Lot than like Lovecraft's shadow haunted Arkham.
Anyway, this is a darn spooky little film which treads the line between fiction and reality that I love so much. The pre-CGI special effects hold up pretty well. There aren't really a lot of effects anyway. Like most good horror films, what you don't see is often more frightening than what you do.