Cinnaess drags the two trussed up ruffians I to the room and puts them in the southwest corner while ushering in the young lady to huddle up on the bed.

"I closed the room doors and stacked the bodies against the far door of that other room. Hunter. Why don't you set that mage in the northwest corner of this bedchamber?"

As she starts walking toward Robwin, she stops and tilts her head (Passive Perception 17), in Elvish she says to Robwin in a low calm voice drawing her daggers, "Young one what is behind the drapes on that wall next to you? I see them shifting slightly."

Robwin comes back to his senses as Cinnaess’s speaks, “What’s that? Oh!.... these drapes?”. He slips the scrolls into his scroll case for now and uses mage hand to pull the drapes back...

Pulling the drapes, you see a partially ajar stone door; made to easily blend in with the wall. It looks like it swings outward from the room. It might have served as a servants passage at some point. The university and your familial home were filled with such things. 

“Ah... A servant’s passage!.... Shall we take a look?”, says Robwin, heading quietly through the secret doorway...

Robwin:

As you enter the passage you see it is the bottom of a narrow staircase that rises steeply up traveling south along the side of the bedchamber.

As you reach the top you hear Cinnaess saying in common. "Stay here child. We locked the door and blocked it. We will be back for you. Hunter. Shadow. The young mage will likely need help. Come on."

As you push open the top door on the east wall, Cinnaess is heading up the stairs. 

This area is the north end of a large natural cavern, but it has been finished with dressed stone block walls and a flagstone floor. Several barrels are stored against the walls here, along with a number of empty crates, straw for packing, hammers, pry bars, and nails.

The cavern continues for some distance to the south. You can make out several passages that open up off the larger cavern, and what looks like a deep pit or crevasse in the floor.

As you're looking around, Robwin, Cinnaess joins you asking in Elvish, "Are you always so reckless?"

You cannot tell whether she's amused, upset or both. 

Rinn taps his chin as the mage hand holds the glass staff in front of him, "I wonder if this is the wizard's staff my new friend mentioned?" He shrugs and carefully wraps it and places with his things before following the others.

Wolfsong follows Cinnaess' request and lifts the unconscious mage over his shoulder like a sack of potatoes then unceremoniously just dumps him into the corner Cinnaess indicated. Wolfsong lets out a small sigh as Robwin goes down the hidden passage before following suit, "Boy should be more careful, we don't know what is around the corner here." 

As you each come into the area at the top of the stair passage make a perception and investigation. 

You have no penalties; you each have dark vision. 

Lia has advantage on an independent perception role or you can use her to help (advantage) Robwin’s investigation.

Robwin’s perception check: 9 

Robwin’s investigation check: 18 

Lia’s perception check (adv): 19 

Rinn's Perception: 21

Rinn's Investigation: 7

Wolfsong Perception: 3

Wolfsong Investigation: 14

"Indeed, I have dedicated my life to doing Kelemvor's work here in the mortal realm. I try to keep those whose time isn't yet finished here upright and moving" TT laughs a bit at the last part and seems positively glowing

In the storage area:

Robwin: Rinn: You notice the creates and barrels seem to be taken good being sorted and repackaged for shipment or storage. Among them, slightly set aside, are thirty nicely done beaver pelts, easily worth two gold apiece. 

Wolfsong: Lia: You notice scuff marks and footprints, though lite, from the south cavern to the eastern wall of the room. There you find another "service door".

Wolfsong: At the door you can faintly hear a voice, "Help us!" from somewhere behind the door. 

All: The dim light you saw previously in this area was probably from the oil lamp that hangs on the wall. It has gone out.

The mansion grounds:

TT: As you, Blaire and Endure reach the mansion grounds, the goblins lead you to a stone staircase just off the empty ruin of a large kitchen. 

"Tracks go there.", Glufs says.

"Well, Let's get on with it.", Blaire says hefting her shield. 

At the bottom of the stairs stands an unlocked door.

Beyond the door, the group, steps into a cellar.

This door opens onto a five-foot-wide landing fifteen feet above a large cellar, with stone steps descending to the floor in two short flights. Another door stands beneath the stairs to the north. A large stone cistern occupies the western part of the room. There is a door in the west wall just north of the cistern. The cellar walls are lined with kegs and barrels.

The cellar:

As the wolves file in past you,  spreading out along the stairs, Endure, looking the place over, says, "This was once 'Tresendar Manor'. Back in 951 DR it was part of a large battle. I don't recall the details. My understanding is only a few times in the past five hundred years has anyone taken interest in it."

"I have certainly wandered up a time or two to picnic on the eastern cliff. I never thought to poke around. Of course, they cleared out that entry way too. I might have ended up following Halia down here if that were cleared out."

"Well, should we call out? See if anyone can point us to this 'Glasstaff' or sneak around a bit to see what is here? I'm not keen on more fighting. It's turning out to be a very long day. Actually, it's already tomorrow." 

She starts chuckling. 

Wolfsong stops and puts his ear to the door then motions for the others to join him a the door. 

"I just heard someone calling for help," Wolfsong whispers. "Could be the others taken from the town, be ready for anything."

Wolfsong grips the handle for the door with one hand while drawing a handaxe with the other, he turns to the others and once everyone is ready Wolfsong burst through the door handaxe held high ready to throw at any Redbrand he sees in the room.

Lia communicates what she sees to Robwin, and he sees Wolfsong move towards the secret door. Robwin nods to Wolfsong, and whispers, “Ready!...”, and he moves over behind his friend and raises his palms ready for anything...

In the storage area:

As with the last two, this "service door" han no lock, it is made to blend in with the wall, the hinges are hidden and it opens into a passage five foot wide west to east and fifteen foot wide north to south. You are on the north end.

Again, the passage is dimly lit by an oil lamp nearly burned dry. Directly in front of you on the east wall is a wooden door with iron fittings and lock; much like the other room doors you have encountered. 

At the south end of the passage is another wooden door.