Vault of the Sevenfold Cipher

The vault chamber is circular and cold, its walls banded in bronze and veined with old green tarnish. Seven ringed dials sink into the floor around a sealed inner door, while four plaques catch the torchlight with faintly luminous symbols that seem almost, but not quite, like letters. A basin of black water mirrors the ceiling, and every few breaths the whole room gives a low, counting hum, as if it is waiting for the right sequence to be spoken in metal and stone.