Hidden in the wild uplands beyond the Selka River, the sinkhole-mine of Delthur’s Folly is a byword among the locals for a fool’s errand doomed to fail. The only survivor of the fated expedition—driven mad by his ordeal and raving of “the water’s sibilant whispers”—died shortly after staggering into Dunstone a year or more after Delthur and his miners disappeared into the wilderness. And yet, every year adventurers cross the Selka in search of the mine—gold and silver are said to lie within. Some return empty-handed and some do not return at all. Local legend has it that something terrible dwells in the mine.

Notable Locations

Delthur’s Folly comprises three distinct small subterranean complexes along with various “outside” locations. Outside locations are numbered 1 - 5. Each of the small complexes has its own key:

• The Watchers: Location in this mini-complex are tagged with the letter A.

• Mine-Home: Location in this mini-complex are tagged with the letter B.

• The Delvings: Location in this mini-complex are tagged with the letter C.

Outside

A path spirals down around the edge of the sinkhole to the mine workings far below.

1 The Crumbling Stair: The Crumbling Stair enables relatively easy access to Delthur’s Folly. 

2 Way of the Shadows: Here, the stairs plunge into deep shadow as they pass under a series of rocky overhangs.

3 The Span: A slender bridge spans the western portion of the Tenebrous Lake. It is entirely without guardrails. 

4 Workers’ Way: A narrow ledge cut into the sinkhole’s flank enables access to the far reaches of Delthur’s delvings.

5 The Tenebrous Lake: The Tenebrous Lake fills the lower portion of the sinkhole. The remains of the orcs’ sacrifices litter the bottom, and something terrible lives among the bones.

The Watchers

Delthur always set a watch here to keep his workings safe from marauding orcs…and worse. 

A1 Guard Chamber: This natural cavern served as a guard room in Delthur’s day. A secret door enables access to the Mine-Home.

A2 The Armoury: This chamber served as a general-purpose storage area. Mining equipment, rotting food stuffs and rusting weapons abound.

Mine-Home

Here dwelt the miners safe behind a series of pit traps of fiendish ingenuity.

B1 Trapped Corridor: Warded by stout double doors, this area was heavily trapped for the miners’ protection.

B2 The Privy: This stinking chamber served as the miners’ privy. 

B3 Kitchen: Here the miners cooked their food. A secret door provides access to a hidden room wherein they stored their supplies.

B4 Chamber of Slumber: A communal bunk room for the miners.

B5 The Hidden Store: Never discovered by intruders or explorers, this hidden room was both storeroom and hiding place.

The Delvings

The lowest level of Dlethur’s Folly comprises mine workings and the mad miner’s personal chambers along with his strongroom.

C1 Workroom: The miners stored their tools and other accoutrements necessary for mine work, here.

C2 Abandoned Mine Workings: This small chamber is played out.

C3 Lair of the Mad One: Here dwelt Delthur in the heart of his workings. 

C4 The Treasury: Delthur kept his treasures in this strongroom, warded by a cunningly trapped portal.

C5 The Deepest Workings: This is the deepest section of Delthur’s Folly

Dungeon Background

Fifty years ago or so, the dwarven miner Delthur Madann came to the borderland town of Dunstone. To the north, beyond the safety of Dunstone’s wall and the Selka River, lay the jagged peaks and deep valleys of the Mottled Spire. The dwarf—a scion of now fallen Vongyth—sought precious metals he could use to hire and equip mercenaries to aid his folk in taking back their ancestral home from its new draconic overlords.

When Delthur declared he was to travel north into the Mottled Spire in search of treasure he was widely derided as mad—the Mottled Spire was an inhospitable place full of danger and hardship. Stubbornly he went anyway, and disappeared into the wilderness for over a year.

He returned with wild tales of a deep sinkhole, a dark and cold lake and a hidden mine. To prove the veracity of his tale, Delthur brought back fist-sized nuggets of gold and silver! He would tell no one where his mine was, but recruited a small band of hardy miners before disappearing back into the wilderlands. 

That was the last anyone in Dunstone saw of Delthur Madann or his band for over a year. Eventually, one of the miners staggered back into town. Badly injured, raving and half-mad the lone survivor of Delthur’s expedition spoke of marauding orcs, Delthur’s descent into madness and the “water’s sibilant whispers”. 

The miner died shortly thereafter without revealing the mine’s exact location or any other news of the expedition. Delthur—and the rest of the miners—were assumed dead and the expedition consigned to history. Among locals, the entire affair became known as “Delthur’s Folly”. 

Occasionally, adventuring bands would set forth from Dunstone with the stated intent of finding Delthur’s lost mine, but none who returned ever reported success. Now locally, the phrase “Delthur’s Folly” has become synonymous with obviously doomed, badly-thought out plans and expeditions. In Dunstone, a “Scion of Delthur” is one marked for an early, foolish death in the lands beyond the Selka River. Many adventurers have thus been named over the long years since Delthur’s disappearance.

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This article is an extract from Dungeon Backdrop: Delthur’s Folly, which is available in 5e, Pathfinder 1 and System Neutral/OSR editions.

Delthur’s Folly also appears in GM's Miscellany: Dungeon Backdrop I (available in 5e, Pathfinder 1 and System Neutral/OSR editions).