Bell will give a running commentary of what she does and does not see. 
The books, the bed, the desk, etc.    She will NOT mention the item around Erudisia's neck.
However, she will describe 'the magic door' she see --

when Bell turns to scan the door, she senses that same feeling. Potential. Conjuration. And more than the door, the wall to either side of it, and, reaching up to the ceiling and bending along it. A large magic doorway dwarfing the actual doorway. Completely invisible to sight, touch, or any earthly sense…

Bell will look again, just to make certain she didn't miss anything the first time around the room and then come back to the 'magic door'.

"Anyone have chalk or drawing charcoal?  I can maybe trace the 'door' ?"  (along side... NOT to cross the streams or lines of magic).   

If anyone has chalk or charcoal, Bell will attempt to trace outside the parameters of what she sees.   Being 'not so tall' though, she won't be able to get super high up the wall and definitely NOT the ceiling!

" So.....if we close this door the magical door will....open....lock this door to unlock the magical door....and then Erudisia says " Sceptre" because she's had the most practise saying it.", Meredith ventured in a rush.

" I only have Ink...and a bit of wax and soap.......sorry, Bell."

"A thought occurs. Do we have a way of opening this dimensional door from the other side? Anything on that in the notes?" Rogi pauses a bit before pointing out the obvious. "It won't do us much good if we go in there and get stuck with no way back out." He thought some more. "Well, we can open it and stay here, I guess. If he's stuck in there, opening it might let him come out."

“Perhaps we can tie some rope to the true study door, or the desk, and so have a way to pull ourselves out,” says Erudisia, happily. 

Since no one else seems ready to volunteer to actually do it, Rogi shrugs and tries to activate the door - making the gesture and saying "scepter" as he does. Hopefully it will open, but he wasn't ready to actually cross the threshold. Not without certainty that he could cross back.  

Rogi closes the door, locks it to silence, then unlocks it once again, allowing him to verbalize the word, "Scepter."

A sudden hum of arcane power: Bvvvvvmmmmmm...

A shimmering, translucent double-door, in appearance like a well-fashioned stained-glass-windowed entrance to a fine townhouse, replete with golden doorknob, appears in the area where Bell detected magic. The doors fully encompass and cover the physical door and wall, and the top two feet of the shimmering doors bend at 90 degrees up onto the ceiling. The doors open outward of their own accord, revealing -- obscured, as though looking through a waterfall or fogged glass -- what could be a comfortably sized parlor, its shelves lined with books.

Meredith watched Rogi in wonder, she hadn't volunteered because she had no desire to mess up in front of the others.....as she likely would have.

Meredith nodded to Rogi, " Thankyou, Sir.".....and stepped into the parlour.....it only occurred to her after crossing the threshold that waiting to check if it was safe first would have been the better option.

Bell is practically drooling at the sight of a comfortable parlor filled with shelves of books.   "Well done, Rogi !"

Erudisia cheers. Then stops as she suddenly realises something. “Is there anyway to close it? And leave through the mundane door?” Then Meredith steps past her and through it anyway. 

“Oh.” 

Meredith feels a tingling sensation at the moment her body passes through the portal, but the sensation ends almost right away as she enters — unharmed — what indeed is a parlor, its walls lined floor to ceiling with books. Hallways branch off from the room to either side and on the right, a finely-joined staircase with artfully carved banisters arcs up to a second floor. Framing the entry door on either side, Meredith notices by craning her head around, are tall windows with sumptuous dressings. Facing the parlor again, Meredith sees a  bouquet of fresh-cut peonies in a fine vase on a side table beside a chaise. On the chaise lies Matreus, snoring quietly. One cookie rests upon his chest, slowly rising and falling with each breath. 

Others: you see Meredith step through the portal and when she does, your view of her becomes indistinct, as if through foggy glass. Vice-versa for Meredith looking out: her friends are only barely discernible. Similarly, when Bell and Erudisia speak, Meredith hears nothing except perhaps the vaguest outline of speech at a great distance. She cannot understand the words. Only Meredith sees Matreus. 

The portal dims and begins to slowly dilate shut, which Meredith notes on her side as do the others from the study room side. 

Erudisia lingers by the closing portal on the side of the study, Meredith an indistinct blur, hesitating. Surely… 

“Scepter,” She intones, while she tears a loose piece of pulp paper in two and scribbles hastily ‘Matreus in magic portal. Went in. Say scepter after door lock and unlock with door closed from inside. Portal opens. Short time! Save us!  (Yours faithfully, in hope of salvation, Erudisia Odewright, daughter of Moonshae, seeker of wisdom and your efforts to our rescue, [to not put too fine a point on it.]).

p.s. will time trapped be counted against our allotted tenday?

p.p.s. I placed an order for a fetching pair of gloves at Erudite Clothiers, as a gift for my sister. I would be honoured if you could be so kind as to send it to my elder sister with my fond wishes, if I am so unfortunate to have miserably perished, as a token of my enduring love from the next world, until we meet again. Thank you.’  

Or at least, she means to. If the command word slowed the portal closure she writes it all, or else she writes as much as she can, throws it onto the study desk, and dives through. 

Besides, she thinks, her Patron can already reach through one realm, what is one more? 

Meredith looks worriedly at the portal but moves quickly  over to try and gently shake Matreus awake.

Quote from NycrolB >>

Erudisia lingers by the closing portal on the side of the study, Meredith an indistinct blur, hesitating. Surely… 

“Scepter,” She intones, while she tears a loose piece of pulp paper in two and scribbles hastily ‘Matreus in magic portal. Went in. Say scepter after door lock and unlock with door closed from inside. Portal opens. Short time! Save us!  (Yours faithfully, in hope of salvation, Erudisia Odewright, daughter of Moonshae, seeker of wisdom and your efforts to our rescue, [to not put too fine a point on it.]).

p.s. will time trapped be counted against our allotted tenday?

p.p.s. I placed an order for a fetching pair of gloves at Erudite Clothiers, as a gift for my sister. I would be honoured if you could be so kind as to send it to my elder sister with my fond wishes, if I am so unfortunate to have miserably perished, as a token of my enduring love from the next world, until we meet again. Thank you.’  

Or at least, she means to. If the command word slowed the portal closure she writes it all, or else she writes as much as she can, throws it onto the study desk, and dives through. 

Besides, she thinks, her Patron can already reach through one realm, what is one more? 

 
Erudisia writes and leaves the note just as the magical doorway is about to close. But when she speaks the command word, VvvvVVVMMmmmm… the portal’s slow closure immediately halts and it glows brightly in its entirety once again, doors opening wide. She walks through, experiencing the same tingling sensation Meredith had a minute ago, and joins her in the book-lined parlor.

Bell notes the fading and reopening of the portal as Erudisia left her note and walked through the portal.   Bell looks over at Rogi, "Guess Erudisia just showed how you can keep the portal open as long as you keep saying the command word.   Do you want to go through?  If so, I can stay on this side.  If not, would you mind if I stepped over?"

Bell looked at Rogi with the biggest pleading eyes - made all the bigger due to her glasses.

Rogi nods and motions at the dimensional door before confirming. "I'll stay here. I'm the one who opened it, I can do so again. Go ahead. If you happen to find any books dealing with magically transmitting information over large distances, I'd appreciate if you brought it back. I haven't been able to find anything I could use in this fortress library so far."  

Bell is already rushing to the portal interface; muttering, "magic transmissions over long distance" as she plunges into the dimensional portal -- keeping her eyes on the blurry shelves of books waiting for her.

Meredith moves to Matreus, noting the small pile of books on a table beside him. His shoulder-length white hair is tied in a loose bun. He is curled in a loose brown cloak over a dyed mustard toga, his face and bare feet showing the same pale vein-covered complexion you’ve grown used to.

When Meredith tries to wake him, Matreus mumbles quietly, chuckling in his sleep, then his eyes flash open and roll in all directions. He seems disoriented and at first barely to recognize you. But he then seems to catch himself and holds still rather awkwardly, though checking to be sure his yoga is covering himself adequately.

“Ah ermmm… Meredith. And Lady Erudisia. How did you?…” He begins, one eyebrow quirked, turning his head toward the portal just as Bell walks through it. At this, his eyes light up and Matreus chuckles rather jovially with a note that might even signal admiration, his eyes following Bell as she joins the others.

The avowed straitens up a bit on the chaise, grunting, his joints cracking audibly, as the cookie that was forgotten on his chest slips onto his lap. His stomach growls audibly as he reluctantly places it on the little side table while with a boyish smile he asks in his rolling Yartarin accent, “Zoh? Vaht do you sink of Fistandia’s mahnsion?”

" We.......I.......all of us......were.....concerned by your long absence..."

" Fistandia?", she turned to the others hoping for help.....it felt like she should know the name but she was rather sleepy.

"Rogi mentioned that name.  Fistandia was a wizard that was a seeker here at Candlekeep.   Of some note, the way he spoke on it,"  Bell spoke over her shoulder as she scanned the book shelves.  "Didn't one of you mention seeing that name in the study room while we were hunting for Matreus?"

“What?? Matreus’ brows rise high and his already pale complexion grows paler yet. “Oh, Deneir help me, I haff been so excited about the discovery of zis place, I…I forgot!,” he says, standing up in a rush and pulling his cloak free from under several books. “You need rrresearch books ahnd scrolls from the library! Of course Ach! I am zoh very sorry! Zis place… its puzzles take time to unravel, and so many interesting books!… Oopsie!”

He has accidentally knocked over a pair of bookends, which clatter to the floor. He bends quickly to pick up one of them, then stands upright, gesturing with it as he speaks. 

“Yes, zis extradimensional space was created by Fistandia. A Wizard who used to study in the room I have been using. I would never have known except that it is my habit to cast Detect Magic when I spend time in a room. Oh! You vahr in my study room? You should not… but I understand. But zen you may haff noticed that all the books were signed by Fistandia? I had to check out and read zeh books she donated to Candlekeep to find out what it was I was detecting. And her margin notes… you must have read them too, to find zeh key word? ”

Rogi hears this conversation only barely drifting through the portal as it closes, then nothing… the portal is now closed.