Excerpt:

Once a zombie senses you, it lets out a long, mournful groan, which is probably intended on making the prey freeze in fear and thus be more easy to catch (zombies are quite slow, if you will recall), but has the added effect of attracting any zombie in the area to the source of the groan. One zombie can easily attract an entire hoard of a dozen or even more in mere minutes – just when you think that you have escaped one, you will find that in fact, you have run into an entire nest… and then you must fight your way out or you are gone. It has happened to Florence and I before. It was one of the single most terrifying experiences I have ever gone through.
(Except witnessing the Fall: nothing can compare to the despair of that moment, of realizing that the concept of Change exists, that even the most shining and bright of us can err so much that they can lose God’s trust and God’s love and be cast aside to a place of Darkness… but even then, in the darkest hour of Heaven’s history, I, personally, had been assured of God’s love and my own continued existence. Staring into the gaping and filthy maw of an incoming zombie (or several of them), one has no such assurances).