Duke Calphat was slaughtered in the War of the Falling Stars, eviscerated by his own men, it is said, in the midst of battle. The soldiery abandoned the field and fled. The man you met was burning his tattoos off with hot blades, "The better to suffer now than be drawn and quartered as a traitor. Kings have no mercy for those who do shirk their gate to die as dogs for their whim."
What interested you most was the plague unleashed, if rumor is true, by Duke Calphat upon his own people. A great tide of death, plague hunters at the borders, and an entire dukedom consumed by death.
This was a year ago, and it has been some time since the last case of the plague was reported by the rumor-heralds.
If you're the first to enter these, then the tombs of the ancient line of nobles will be unguarded. Untold wealth for the taking.