Machi-e recognizes some of the drawings in the book as depicting aberrations associated with the Dark Tapestry.
ETA: On reporting to the Baroness, she expresses her satisfaction with your work, and pays you the 5000 gp fee. "You did your work quickly enough that the assessment will be done long before the auction is scheduled. You may attend the auction, if you wish, and if you want to bid on any of Hunclay's belongings I'll cover half the price of anything you're interested in--up to 7,500 gold total among the four of you."
The auction is scheduled for a month hence, so you have some time to yourselves.
No one currently in the town is interested in buying the books, but it's possible that one of the visitors who comes for the auction would be willing to pay.
Magical dust in hand, you return to the basement of Hunclay's manor. Machi-e takes the contents of a vial and tosses it into the incandescent wall. As each grain strikes the wall, it leaves a dot of darkness, spreading across the face of the wall of light and into it. In a matter of seconds, the spell effect is gone, leaving only the glimmer of light from an everburning torch nearby. From down the hall you hear a woman's voice call, "Arien? Rowane? Is that you?"
"Why, yes it is..." Rowane answers the voice.
Not being Arien, Cora remained silent as she peered through the darkness.
A shadowy shape emerges from the hallway, surrounded by an aura of darkness. "I am eternally in your debt, friend Rowane. And your companions, as well." She addresses the rest of the party. "I am called Maffei. The foul wizard Hunclay had imprisoned me here after summoning me and pestering me with his foolish questions. But now, thanks to you, I am free."
"Now that you are free, you mind answering some questions?" Rowane says putting his hands on his chest and tilting his head forward. "What questions did he ask."
"Hunclay fancied some sort of link between the Plane of Shadow--my home--and the Dark Tapestry. There is no such connection. He was so convinced of it that he continued to press me with questions about it. When I mocked his ignorance, he struck out at me with his magic and imprisoned me behind the light wall. Three times I tried to escape, but the wall's power left me weakened to the point where I dared not try again. That weakness remains with me. Still, I am in your debt."
"Interesting." Rowane says thinking out loud. "Of course they are not connected, that is common knowledge. Do you know of any other beings possibly trapped? Or, did you hear what is next move would be?"
"M'Lady Maffei, I am Machi-e," says the arcanist, bowing. "We would be most grateful if you knew why he was researching the Dark Tapestry. I understand that he was investigating planets, possibly to see if one was connected to this...subject matter."
"I do not know."
Machi-e, after reviewing the information in Hunclay's notebook, looks up.
"So. He was an idiot."
"Not an idiot, I don't think. The... beings associated with the Dominion of the Black aren't of this plane. To think the inhabitants of the other planes, especially those like nalfeshnee or the servitors of Abraxas, might have knowledge of the darkness between the stars is not a foolish belief."
"Someone who summons something they cannot control or understand fits my definition of an idiot," says Machi-e flatly. "They would be removed from Magaambya at once and stripped of all degrees."
"Ah...Lady Maffei, please excuse my insouciant outburst; it was very unbecoming. You are still weakened. How may we remedy that?" The Mwangi recovers his charm smoothly enough.
From Maffei's description of her symptoms, and from Machi-e's review of Hunclay's wall of light spell, you are able to determine that she has taken three permanent negative levels. It will take restoration spells to cure her.
"Maffei, we'll have to call upon the graces of our patroness, or sell something, to help you out. In the meantime, perhaps we can find a place for you to lodge and hide in town."
Over the next few weeks, small groups of unusual travelers converge on the village, obviously awaiting the auction. They include a trio of white-clad Kalistocrats from Kerse in Druma; two black-robed individuals of indeterminate gender representing the Mercantile Consortium of Maheto; a perpetually angry-seeming half-orc named Mr. Pickets, who represents a Taldan duchess from Cassomir; and a rather standoffish man named Clausyre, who claims to be a factor for an unnamed individual "from the North."
The Baroness privately expresses disappointment at the paucity of bidders, but Belhaim's remoteness and Hunclay's limited fame both work against her. A large number of locals attend, though many are likely there out of curiosity. Due to your part in securing the estate, you have the opportunity to sit in front.
"Well, friends, here's the conundrum; do we save our gold to buy something from Hunclay's possessions, or do we cure Maffei of her ills? It would seem that we can sell a few items, ourselves. I would be the one most likely to buy items, but it remains to be seen if I'm feeling up to it, all circumstances considered," intones the Mwangi.
Machi-e considers what to wear for the auction.
The day of the auction dawns clear and temperate, with only a mild breeze to stir the air. You find your reserved seats in the front of the open-air amphitheater where the festivities are to take place. The visitors are seated in the first couple of rows, along with those locals who have come to bid on items. The lots are all set up in a row along the rear of the stage. The auctioneer, a gentleman named Chosk Grellen, is up on stage with several guards detailed to watch the lots. Some of the potential bidders are also on the stage, looking over the items for sale. As you sit down, you notice Clausyre arguing with the auctioneer. The visitor seems to be quite flustered.
Machi-e stands back up again and walks up on the stage. He speaks to Chosk. "Is everything well?" he says mildly.
The auctioneer starts to respond, but Clausyre cuts him off. "This cannot be all there is! Hunclay must have had more--something is missing, and the Baroness must be holding it back!"
Chosk holds up both hands in a conciliatory gesture. "I will arrange for you to meet with the Baroness, but not until after the auction. Will that be satisfactory?" Clausyre seems to be placated by the offer, but it's clear to Machi-e that he's not happy.
Cora wanders through the items on auction but doesn't move to interfere in the argument between the man and the auctioneer.
Machi-e raises an eyebrow at the exchange, but offers nothing further. He scans the items, comparing them against his own mental checklist.
All of the items on the stage came out of the manor, and nothing that was in the manor is missing.
Machi-e manages not to bump into anything visible or invisible. That he knows of.