This wasn't the first time Isabelle fell somewhere.  She has tripped on rocks, branches, toys, everything you can imagine, and what she could likely imagine anyways.  But this was the first time she outright fell into the abyss, and the girl from Missouri doesn't know what caused her to fall, she wasn't really paying attention.

Isabelle had awoken in a room of some sort, and she was lying on some pillows.  While she was pondering where she was, the girl heard someone speak.  And it was a kitty-cat!  And a talking one, at that.
"Hi!  I'm Isabelle!"  The girl reached out to pet the kitty.