The citadel of Genzacon looms over the Gloomport beneath Darkenhaven, standing watch against the horrors which periodically emerge from the passage leading into the Underdelve. Yet all is not well in the formidable keep, as there has been a murder amongst the leadership of the Genzacon Guard.

Charged with investigating this unusual killing, you swiftly find that the situation is far more tenuous than you could have imagined. Several others have gone missing in recent days, ever more deadly foes assail the gates, and suspicion is building between life-long allies. The evidence is there to unravel the mystery of the castle, but can you put the pieces together in time?