10 Horror Movie Endings That Made You Say WHAT?!
4. In The Mouth Of Madness
In The Mouth of Madness, John Trent is an investigator who's tasked with tracking down hack writer, Sutter Cane, who has gone missing. Believing Cane's disappearance is a publicity stunt to promote his new book, Trent is certain he will find the writer. But as Trent stumbles upon all sorts of otherworldly horrors, he becomes terrified that he may lose his life, his mind, and his soul.
After Trent encounters Cthulhuesque monsters, demon children, and tentacled motel keepers, it's no surprise he ends up in a psychiatric institution. The day after he recounts his experience to his doctor, he discovers the asylum has been abandoned. Upon exploring the city, he sees that monsters have taken over the world.
Upon learning he has basically woken up in the apocalypse, Trent does what anyone would do - He goes to the cinema to see the movie adaptation of In The Mouth of Madness! (The poster even mentions that it was directed by John Carpenter.) Watching himself on the big-screen, Trent maniacally laughs to himself before breaking down in tears.
So, what happened? Is Trent crazy? Is he a character in Cane's novel? Is it a little bit of both, or something inbetween? You decide.