As they wander back towards the manor and the ladder down into the ground, Triäsa calls over to Daventry. "Do you want to dig up Fistandia's grave? I do wonder though, wasn't she something of an expert an trans-dimensional spaces?  And here she is buried at some spot that supposedly has a permanent portal of some sort. I presume it has to be under the house."

"No that grave is no more Fistandia's than the one beside it is mine." Ludolf says, ready to follow Daventry down the worm-infested tunnel.
Stealth: 12 Perception with help from Edgar: 21

You slowly one by one descend the ladder down into the cold dark earth. It's pitch black but with your combination of dark vision and light sources you can see this is a tight corridor that leads to some sort of root cellar. There are collapsing shelves along the walls and the air is filled with a putrid rotting smell from the decay vegetables strewn about. For the first time since you have climbed the mountain you do not notice any mist.

Ludolf and his trusty companion searching the room notice one of the shelving system is oddly intact and further  inspection shows hinges indicating some sort of door. This shelf swings freely outward toward you to reveal a small room only about 15feet square. The room is pretty bare, there are two boxes sitting carefully on a wooden table laid in a purposeful manner. 

"Pardot, a hand?" Daventry cautiously takes a look at the boxes, examining them (and the table) for traps, removing her kit from her belt pouch.

If untrapped, she'll try to open. If trapped, she'll disarm first.

Investigation: 16, guidance 3

Thieves' Tools: 19, guidance 1

Ludolf stands back a bit when Daventry starts her investigation, trying to get Triäsa to stay back a bit as well, as best he can.

Daventry you look over the boxes and you quickly learn the following details.

You look at the wooden box and see it has a small lock, quickly you look at lock and find that it is not trapped and deftly you pick the lock and it pops open with no issue. Perhaps as an after thought or because this has happened before you think of the key Pardot found earlier. Inside the box you find a small book bound in leather. It is very plain, very small. It has maybe 50 pages and appears to be either a notebook or a journal.

There is no obvious way to open the metal box it is heavy, alot heavier than you would expect given it's size. The metal box is a plain platinum box it has no obvious lid and is about 4 inches square. On what you presume is the top you see the strange shape from the caves etched deeply into the lid. As your gaze falls upon it you feel very strange and feeling of impending doom and deep fear. 

DC 12 Wisdom Save or become frightened of the symbol for 1hr

Triäsa, standing back behind Ludolf, watches as Daventry opens the box.  She's intrigued by the small book. Not really seeing the symbol on the box, she suggests, "Maybe the book explains how that other box opens?"

Daventry Wisdom Save: 18

Daventry is able to regain her composure and steel her nerves against this feeling. You carefully place the box down on the table.

In the small room there does not seem to be anything else of interest.

Ludolf telekinetically brings the small book to him and starts to read it.
Investigation if needed: 18 + Guidance: 3

Ludolf you are intelligent enough that with enough time you can read the short note book rather quickly. 

The notebook in the small room contains notes on experiments and observations from Baron Brantiflax. Thumbing and reading through the notes you learn that he an eccentric man obsessed planar travel. The notebook details his search for a way to travel planes. The scratchy erratic writing tells the story and his quest for passage beyond this plane. A few entries you find  particularly interesting.

Daventry seems pleased with the practice on the lock, even if they had the key... and hopefully she was instructional to Pardot.

After examining the metal box, she takes off her cloak and wraps it up, covering the unsettling rune. 

"Right. That thing is kinda creepy... but I feel like it's important enough to be worth keeping." She is about to slide the box into the bag of holding, but then thinking on what she knows of such extradimensional bags, decides just to stuff it into her normal pack.

"Ludolf? You look concerned. What's the journal say?"

"Yes, what does the book say Ludolf?" Triäsa says, trying to look over his shoulder. 

"Fascinating." Ludolf says as he quickly reads through the pages. "This seems to be the journal of Baron Brantifax." He says and reads aloud the entries he found interesting. "The man in black must be the shadow I spotted earlier. But the last entry, did he open the portal by going into his own grave?"

"No!" Triäsa says quickly. "You are not going to do that Ludolf!" she adds, looking directly at him and grabbing his arm.  She then quickly seems to compose herself, letting go again. "I mean, there must be another way.  If someone is going in there it should be me. I can transport myself back out quickly if necessary. And besides, what I do is already somehow shifting through planes, so, yea, that would be best." 

"I'm not saying I'm going to do it Triäsa, but under no circumstances are you going to. If anyone should do it it must certainly will be me." Ludolf says like there is no point in discussing that further. "I have some knowledge of planar transposition myself and if someone should take the risk of dying in that grave it should be the one that already had a long life. And besides, it might only work with me considering it is my name on the headstone."

"Umm, yes, thanks Klin, but as I said I'm not going quite yet I think, we still have that box to investigate." Ludolf says letting the monk keep his book, giving him an awkward pat on the back as he hugs him. "What do you think Daventry, can we have a look at that box? It might give us some clue on how we should proceed."

"Aye, fine. Gird your loins. This thing is weird."

Daventry reveals the box to anyone who wants to take a look at it.

"And this is coming from the chick with the book that makes you go insane, so..."