And with that, Vargun leads the PCs out of the Sorry Excuse and back down to the center pool, clockwise around the inner edges of Hospice right to where it meets Downmarket, but then south away on that central path from there. She leads you through the gated section into the Highside Stacks, an upper-class neighborhood. Here the rich dwell in tall buildings overlooking the Core Districts, far removed from the chaos which characterizes the rest of the city. Some of the inhabitants of the Stacks sequester themselves completely from their neighbors, handling all day-to-day necessities through servant intermediaries.

Continuing south and up you get to the southernmost portion of the Highside Stacks and cross footbridges where a confluence of streams frame the Therassic Spire in picturesque fashion. Often called simply the Great Library, the Therassic Spire is believed by many to be the oldest repository of written knowledge in Varisia. A circular tower eight stories tall, the structure is rumored to extend an equal number of stories belowground. The librarians who run it are a reclusive sect that lives within its walls, and part of the library’s fame comes from the fact that all knowledge is welcome, no matter how trivial, dangerous, or profane—though finding it in the twisting, bizarrely organized stacks is another matter entirely.

When Vargun and the PCs approach, the huge iron-bound doors of the library are shut tight, a small, meticulously lettered sign announcing that the library is closed until further notice. Vargun ignores it and pounds on the door with a meaty fist, keeping it up for a full minute. At last, a panel in the doors slides open, and a pair of beady eyes stare out through ornate metal grillwork. “If you can’t read the sign,” a prim voice says, “then there’s nothing in here for you anyway.”

Vargun lets the PCs take the lead in the conversation. Since it is the Pathfinder's mission and The Scribe is the better conversant, he begins to talk to her, and the librarian does her best to heap abuse on him, but as soon as The Scribe mentions the "Council of Truth," the eyes behind the grating go wide, and then the door cracks open. A hunched human woman in red robes ushers them inside quickly, closing and barring the doors behind them.

The librarian’s name is Koifa (female old human). Once she has asked enough pointed questions to ensure that The Scribe actually knows what he's talking about, she sighs irritably and explains the library’s situation..........

Unbeknownst to most people, the librarians of the Therassic Spire are not the first scholars to take up residence in Kaer Maga, nor are they the best. Far below them, in a subterranean realm called Xavorax, dwells a race of extraplanar researchers and historians known as the caulborn. Much like the giant monument-city itself, the caulborn predate the empire of Thassilon, and even served the runelords for generations before finally being driven below the surface by the calamities of Earthfall.

In recent years, the librarians of the Therassic Spire have occasionally made telepathic contact with the caulborn in order to answer specific esoteric questions, though always at a price.

Koifa attempts to brush past the matter, but when pressed by The Scribe, she reveals that the caulborn consume thoughts and memories, and that their payments always take this form.

Weeks ago, however, the caulborn contacted the librarians directly, offering to help the surface-dwellers recover an artifact of great power—a shard of Xin’s great Sihedron—from another legendary realm below the city called the Dark Forest. In doing so, the caulborn revealed to the librarians something none of the scholars knew: that their own tower contained a secret door, hidden for thousands of years, which leads down into a hitherto undiscovered portion of the Undercity that contained one of Karzoug’s many workshops. The caulborn informed the librarians that if they could send a band of adventurers or mercenaries to meet emissaries from Xavorax in “the chamber of the black menhir, beyond the River of Memory,” the caulborn would aid that band, using the black menhir to transport the adventurers to the heart of the Dark Forest, where the blind creatures’ research has indicated the Shattered Star fragment rests.

Ever enigmatic in their ways, the caulborn had little more to say on the topic, but what they had said was enough. Greedy for the chance to study the item and chronicle its recovery, the scholars agreed, and under the pretense of resurrecting the great Council of Truth, the librarians recruited an adventuring party to travel into the hidden dungeon below to meet the caulborn emissaries. The entire endeavor—to send the recovery team down through the lost workshop to the meeting point with the caulborn, then into the Dark Forest for a quick snatch-and-grab—was supposed to take only a few days at most.

Yet something has gone wrong, and the team hasn’t returned, nor has it apparently reached the rendezvous with the caulborn. Fearful of what they may have awoken in the city’s depths, the librarians set up a constant guard around the secret door, and dare not let anyone into the library for fear that visitors might notice something amiss and contact the Duskwardens. (The whole operation is highly taboo, as unauthorized expeditions into the city’s depths put the whole populace at risk of increased monster activity, and the library wants to avoid responsibility for any death or damage their hubris may cause.)

At this point, Koifa really just wants the whole problem to go away. She fears a possible scandal, and is desperate for someone competent to fix whatever’s gone wrong. The PCs give her hope—if they can delve into the chambers beyond the secret door, find out what happened to the team the librarians sent down there, ensure that the caulborn emissaries haven’t been harmed or otherwise betrayed, and then continue the mission to retrieve the fragment from the Dark Forest, she agrees to let them keep whatever treasures they find in the chambers below, including the so-called Runelord’s Shard.