faces of fear by Dean Koontz Unabridged

You and your friend Sarah are being chased by a homicidal maniac through an office building in the middle of the night. You take refuge in an empty office like frightened cockroaches, but the doors are forced open, revealing your antenna-quivering vulnerability. In desperation, you scramble up and down elevator shafts with one lame leg dangling helplessly behind, and try other life-threatening feats that seem to be more appealing than getting an ice-pick through your skull.
The most horrifying thing about this scenario: the person chasing you is not a disgruntled co-worker, and it's not your boss! It's a notoriously murderous rapist, and he's just about to get you or Sarah every turn of the way. And then you remember the terror of falling while climbing Mount Everest and you think you've figured out how to escape... but have you? You still haven't figured out who will be crushed by the monster snow-plow!