From the introduction:
There are those who travel through time, bodiless and undimensioned, inhabiting the corporeal forms of things of matter when it suits their purposes dark and unknown. The Great Race of Yith uses this method in pursuit of its great work. They are the only race who has conquered space and time so thoroughly.
But there are those who have forgotten if they were ever part of a race, if indeed they were ever anything other than what they are, incomprehensible mad destroyers and dark forces in the obscure and unknowable corners beyond reality.
User summary:
This scenario typically is distributed as a ZIP archive containing several RTF documents:
1-page introduction
12-page scenario
7-page non-player-character details
4-page print-and-play handouts