Sometimes your imagination intersects with the players in a way that becomes... unexpected. I freely admit I can occasionally spin a game sideways and follow my instinct for a story line into new territory. Everdark is a case in point, when my dice had a mind of their own and a routine dungeon encounter led to years of player enjoyment.
To set the scene, an adventuring party was exploring in the area known as the Cemetery Hills. The Cemetery Hills are a necropolis, where the remains of the undead armies from the Necromancer's Revolt (AE573 - AE 647) were entombed in an older area of burial sites. There are monasteries around it and roving teams of priests to keep things under control. Permits to retrieve items and pursue undead who have preyed on the surrounding lands can be acquired.
Around AE 933 the adventurers were searching for some rampaging ghouls, and had fairly good info as to which area they might be in. The site was in one of the high risk areas of the Cemetary Hills. What they found was a pair of Shadows, terrible Undead / Negative Planar creatures. The group managed to retreat with several gravely injured members. A local priestess was willing to heal the Shadow marked characters, but required an oath that the group destroy the Shadows.
I'd designed a pre-built NPC monster, an Arduin style Boogie Man, who could be the creator of the Shadows. Originally intended as a high end contract assassin, but what the heck, I needed a tough monster and was feeling lazy. When they returned the Boogie Man and his cultist minions were almost more that the party could handle, until a player managed several critical hits on the Boogie Man in close combat. She was immune to his contact drain attacks and he really wasn't ready for full contact fighting. When he attempted to escape she grabbed his lair key and prevented it from going with him. That wasn't in my plan, but... improvise.
Once the players returned to town they spent a fortune or two on divination's and specialty mages to figure out how to reach whatever the key guarded. That is an entire story, currently about 50k words.
From the Players Guide:
EverDark Trading Company is a major player in the City of T'Ell shipping. The current House is based on the charter of a Drow household that was obliterated in the Necromancer's Revolt. There is some evidence that the older version of the house attempted to double-cross the Necromancer by taking funds to open ways into the city, then betraying his forces when they attempted to Capture T'Ell in AE 627.
The disappearance of the House and hiding of most of it's facilities is believed to be from an Obliteration curse, that makes all knowledge of the target disappear, even to members of the house itself. Even records not protected by magic will blank out the names and locations, leaving blanks.
Eventually the curse wore out, being broken around AE 905 by a party of adventurers. [ETC_Roots story]
Reactivated AE 906, rejoined Council AE 956.
EverDark Trading is partially owned by Lady Tabitha Demonde, along with both the Midnight Rose properties. EverDark acts as the facilities and supply arm for the Midnight Rose Inns and engages in significant cross world trade.
Managing partners: Karla Demonmoon's Daughter, Tylindal, Chessa O'Donnell
Warehouse Manager: Oscar O'Donnell
Recently an entire EverDark party was reported lost while searching for a lost caravan from N'Draka. It is reported they were swept through a rogue gate in an accident. The event was reported to be somewhere in the UnderDark near the city of Cord. Statements to claims adjusters by House EverDark indicate they do have contact with the party and expect to retrieve them and portions of the missing cargo.