Shortly before the Shadowing, Streck Nirduk disappeared.
Shortly after the Shadowing, Elbret Shorin attempted to ransack the Nirduk Vault. Ganeth and Kelmin Northstar delayed her by collapsing the Nirduk base (set in a plateau in the mountains north of Cthul-Ra), burying the Vault entrance and the Nirduk clan's transit pentagrams under tons of rubble.
After a failed sending attempt, Nomistrus and Lord Rogtubbins declared Streck officially missing or dead and unsealed his will. The information inside told Ganeth how to access the Vault and create a new, secure combination. The party (with some help from Lady Rognukena's miners) and the Shorins then raced to unearth the Vault; the good guys won, and Ganeth got inside to change the combination.
Some time later, the party needed a transit pentagram to slip into Silverton, so they headed back to the base. They learned that a rogue Death priest named Kharnzeel had taken up residence there, remodeled the place, and fortified the area with elemental earth and air creatures. The party defeated the guardians and used one of the pentagrams.
The party soon learned that Kharnzeel was probably Asmo's top mortal in the area, overseeing operations related to the Keeplands, Banzeel, and the war. He was also implicated in Streck's disappearance and lots of other evils the party had been running across. The party was able to capture Kharnzeel's bonded bodyguard Subator, cut off his access to the karfu (evil black birds in sizes from sparrow to roc), and foil some of his operations around Lifeblood Forest, but the war and Ganeth's kidnapping prevented the party from mounting an assault on Kharnzeel's headquarters in the Nirduk Vault.
Now the war is over. All the mortals and extraplanars in the area are in turmoil. And Ganeth's decided that the ultimate solution to the Vault problem is to move it someplace more defensible, to keep it from being infested again if the party manages to clean it out.
The basic plan is to hire Fraxiz's inventor corps, head to the base, dig up the Vault (using dig spells for the dirt and stoneshape for the rubble), have the gnomes break it down into its constituent pieces, reduce the bits for transport, and teleport the whole mess to the Hollerith temple for safekeeping.
Looks easy on paper, doesn't it?