The Roadkill of Middle Earth

Middle Terra Firma was home to an idyllic countryside and a wondrous variety of fantastical beings and magical inhabitants. It existed in peace and contentment, until the arrival of the creature known as The Dark Rider, and the havoc he wreaked as he traveled the Black Highway in his sixteen-wheeled dragon.
To quote from The Book of Roadtrippin' by Bivouac, son of Carouac: "It was he, The Dark Rider, who was in the driver's seat, and his wicked hands were clasped firmly on the wheel. Where he came from and where he was going nobody knew, but one thing was sure...there was no mistaking where he had been." Who is this terror bringing death and destruction to the magical land? Who are his victims and who has survived? What is his dire purpose...and where will it all end? Come, gentle readers -- be not afraid. The tale within these pages will explain all...except how to best prepare...