From the introduction:
This is a table-top role-playing game set in the world of Neil Gaiman's novel (and television series) Neverwhere. These pages have all you need to learn the basics of West End Games' D6 system, create your own characters, and run adventures in the Underside.
The world of Neverwhere exists parallel, aside, and under our own. In the subway systems, forgotten sewer tunnels, the shade of alleys, and the corner of your eye, a whole population of folk eke out a daily existence in a world full of magic, danger and endless, swirling surprises. These "underdwellers" pass invisible, right in front of our eyes, acknowledged for only a split second, but never recognized nor remembered. In their world, favors form the only real currency, alliances shift with the hours, and surival requires wits, brawn and more than a little luck.
Say goodbye to your boring, mindless job, your bland little cubicle, and your safe predictable life. You've just fallen beneath the cracks of the everyday world and into the shadows of the Underside.
Welcome to Neverwhere. If you can survive the first day, you just might make it a week..