SFWA Grand Master James Gunn's This Fortress World takes place in the far future of our galaxy, when countless civilizations have risen and fallen, leaving only their marvelous scientific achievements as legacy to those worlds which have now fallen into a new Dark Age. On the planet Brancusi, William Dane, an acolyte monk in the all-powerful Church, comes into possession of a crystal pebble dropped in the offering plate, a stolen treasure believed to hold untold secrets of mankind's past. There are powerful men who will stop at nothing, including murder, to recover this ancient artifact. Ignorant of the outside world, who can Dane find to help, and who should be trusted with the pebble's secrets?