“The fortress fell three centuries ago. What replaced it remembers every soul that died inside.”
The party is hired by Lady Selwyn Thorne, a merchant princess whose trade caravan was ambushed by creatures emerging from a sinkhole three miles outside the city. The creatures carried pieces of her stolen cargo — goods she was transporting for the Velton Merchant Consortium. The sinkhole leads to a network of vaults and chambers that were once the keep's lower floors. Something has been living down there. Something that is very much awake.
Themes — The weight of oath and consequence. What is taken from the earth does not always stay taken. The darkness in people surfaces when the light fails.
The party descends into the sinkhole, establishes a forward camp, and explores the first vault complex — encountering the remains of the caravan and a group of hostile survivors camped in the old granary vault.
The sinkhole is a 40-foot vertical drop through ancient stonework, ending in a rubble-strewn entry chamber. Rope ladders can be rigged with a DC 12 Athletics check or purchased from Lady Thorne's supply master. Below, the old keep's ground floor has partially collapsed into the vaults beneath — the result of centuries of water damage and a recent tremor. The party must navigate uneven floors, flooded chambers, and the lingering presence of whatever ambushed the caravan. The first encounter is not monsters — it is evidence: scattered cargo, broken crates, signs of a fight that happened and ended badly. Then they find the survivors.
The party descends to the Deep Vault, encounters the Warden's lieutenants, and learns the history of the Hollow Fortress's final days through environmental storytelling.
The Deep Vault is a massive cylindrical chamber — 60 feet across, 40 feet tall — that was once the keep's primary treasury and war room. It is now the domain of the Warden, a bound spirit that has maintained the fortress long after its fall. The party encounters two of the Warden's champions: Sergeant Corvath, a shadow knight who serves as the Warden's enforcer, and Lyrell the Dread, a chained sorcerer kept alive by the Warden as a living prison for something she did centuries ago. The session alternates between combat encounters in the vault and exploration of its upper galleries, where the fortress's final hours are preserved in carved murals and scattered remains.
The party confronts the Warden directly, learns the truth of the fortress's fall, and makes a choice about what to do with what they find.
The Warden is a bound spirit — not undead, but something older and stranger — that was created when the fortress's last commander, a paladin named Aldric Vane, sacrificed himself to seal a breach in the earth that had opened beneath the keep. The breach was not a natural phenomenon. It was a wound in the fabric of the world, torn by something that was trying to enter. Vane bound himself to the fortress as its guardian, and the Warden was born from that binding. Three centuries later, the binding is weakening. The Warden has been drawing the life force of those who enter to sustain itself. The creatures the party has been fighting are not monsters — they are the fortress's last defenders, bound to the same oath Vane took.
