From the introduction: This sprawling closed-earthwork fortress is built atop an islet known as Carruth Rock. Beneath a section of the bulwarks is the Research Wing – a cluster of ruddy stone rooms and hallways that was recently in the vanguard of arcane technology. Sealed after an unexplained incident, the facility is being overrun by (disturbingly homogeneous) Albino Dire Rats. The rat horde only seems to be increasing, and the research sponsors want answers.