"The walls began to pulsate more quickly, and that was when Tom knew there was something behind him. Something dark, malevolent, and voracious, watching him intently."
“It's a dangerous business, Frodo, going out your door. You step onto the road, and if you don't keep your feet, there's no knowing where you might be swept off to.”
-- J.R.R. Tolkien, The Lord of the Rings