Pure science fiction can be a lot more horrible than “horror,” or even “SF/horror.” The scope of its imagination can doom the entire planet or create an unspeakable institution that operates on too subtle a scale to really fit in with “the horror section,” yet inspires awful thoughts that stay with you for days.

I respect this sort of thing, when it’s done well. But when a book is really, truly horrifying, reading it is about the extent that I’m prepared to allow it into my consciousness. Since the #1 book on this list was made into a film quite recently, I figured it’d be a good time to list the five SF books whose films you couldn’t pay me to see.

5. Fahrenheit 451. I have yet to read a more damning account of a civilization committing suicide from within. It’s the least depressing on this list because the ending is somewhat hopeful, but Bradbury’s ideas actually frighten me more with every passing year.

4. 1984. Despite its practically defining rendition of SF dystopia, the book throws out just enough breadcrumbs of hope to make one believe that the human spirit might prevail. Spoiler warning: “Imagine a boot stamping on a human face– forever.” That’s kinder than what we get.

3. One Second After. It’s not a movie yet. Maybe it never will be. Because maybe an electromagnetic pulse will wipe out America’s power grid and, essentially, America’s civilization too. I’ve seen some of the novel’s underlying assumptions challenged, which comes as an immense relief, but I still find it wrenchingly plausible, with a could-happen-tomorrow feeling that is extremely difficult to shut out.

2. The Road. Oh, God. The last days of mankind, at least as far as we know, are rendered in brutally well-thought-out detail. I guess the ending isn’t a complete heart-fisting, but the path we take to get there… the endless grayness, the carnage, and especially the flashbacks to the wife… Man.

1. Never Let Me Go. They’re… they’re being grown for parts. They’re kids. Just kids. They won’t get to stop being kids. There’s a… schedule, and… and… Jesus…

Fuck everything.