It was the result of 1 hour of thinking and coming up with nothing. Then I stared off to the wall and one of my favourite songs started playing in my head (there is always a song playing in my head)... and it was Radiohead's "15 Step", the lyric of interest being 15 steps, then a sheer drop.
You Twilight fans may recognize the song from the end credits of the movie, when Victoria walks down the stairs. It was the only part of the movie I actually really enjoyed since I was happily surprised that one of my all time favourite songs was playing. :)