The Black Isle, which juts darkly out of the River Reik, is the the grim island stronghold of the Altdorf Black Chamber, the best-equipped spy organisation in the Empire.[1a]
Although the cannon-guarded fortress of the Black Chamber is on an island in the Reik, it is still connected to Altdorf's city walls. The Imperial spies get to choose the state troop regiments that garrison the tower. They tend to select soldiers they believe to be skilled, patriotic, discrete, and able to ignore the sounds of torture that invariably emanate from Black Isle.[1a]
The Black Chamber is not exactly secretive about the sort of activity that goes on in their fortress. Indeed they intentionally cultivate an aura of menace by lining the castle's ramparts with the decapitated heads of traitors and heretics.[1a]
Aside from being a site of dread for enemies of the Reikland, Black Isle also threatens river traffic on the Reik. Many boats have been wrecked against the jagged rock, especially during Altdorf's famous episodes of fog.[1a]