Whats the first book that seriously scared you?

[Chocolatl]

Sphere by Michael Crichton.

When I was a kid, my dad travelled a lot. We were living in South America at the time, so my access to books in English was rather limited. Dad used to pick up novels as he stopped in airports here and there, and then pass them along to me -- so I ended up reading books like Jurassic Park and Sphere at the age of nine because they were all I could get my hands on.

Anyway, Sphere scared me badly enough that when I was done reading for the night, I would put the book in the freezer so that nothing could manifest out of it while I was sleeping. I had heard about little kids getting trapped in the fridge, so I guess I thought that any evil creatures that manifested would not only be trapped but would also freeze to death.

ETA: I just glanced at the bookburning thread and am amused to find that several people seem to have hated this same book.