There is no need for perception and nothing to perceive either - the room is almost empty. Almost. It is lit by a pair of tall wrought-iron candlesticks in the northeast and southeast corners. Nine candles burn atop each one, casting flickering light across a claw-footed altar carved from a single block of obsidian, and which has a small angel-shaped flame erupting from its top. A gray-haired woman stands across the room by the wall, opposite to the one you came through. She wears fine clothing fit for a noble of a high stature and carries no weapons. The look on her face is cold as the Great Glacier.

"Why are you here? I though I made it clear that no one can disturb me at that time. Whatever is it you need - Odious will handle it, now - be gone!"

Choir is hiding behind Nibs, and the scary lady does not make her eager to change that.

"Mi lady, dead.  They are all dead.  The fist, they are here!" Adray shouts out to her.  He waits a moment to catch her reaction.  The moment she begins to speak, what ever she says, he rushes forward and punches at her face.  He then kicks hard at her knee to knock her down.

Move: close the distance

Action: Punch Attack: 16 Damage: 7

Bonus Action: Spending Ki Point for Flurry of Blows, any strike that hits her she needs a DC 13 dex save to avoid being knocked prone

Flurry 1 Attack: 5 Damage: 7

Flurry 2 19 Damage: 8

If flurry 1 hits and she is knocked prone, flurry 2 is at advantage, here is the additional roll if needed 17

Dex save: 2

Not even asking the name of the old lady or what business she has in the dungeon, Adray attacked - and succeeded at every hit! However, the lady, despite her visibly twilight years, did not look a bit as a noble delicate flower - barrel-bodied, with strong hands and forearms she did not even flinch under the flurry of blows. But she did not attack herself either, instead she stepped back, closer to the wall, while Adray found himself engulfed in flames:

Roll DC 14 Dexterity saving throw, taking  22 fire damage on a failed save, or half as much damage on a successful one.

While Adray was busy with extinguishing flames, woman disappeared leaving behind black smoke - very familiar one, last time you experienced that very smell and impenetrable darkness was not long ago in the Lower Lantern, when you were chasing Amrik.

Soft click in that darkness and sound of some kind of mechanism was all you could here.

 Choir was shocked that Adray attacked the old lady, but she supposes that they are in a bad people's place, and the lady was definitely not nice--maybe the villain they are looking for.. She searches to see if the lady went through a secret door. Investigation 4

Brave kenku dived into the smoke, covering area where the woman had stand, but even the light of the mace was still not enough to see anything just yet. By the touch alone it was not possible to tell if there is any door.

Dex save: 25

Actually, if every strike hit her, then she would need to make a second save against the 2nd flurry attack that hit.  If she fails that, then she would have to spend 1/2 movement to stand and could only run 1/2 her speed unless she took a dash.  If she took a dash then he wouldn't get attacked.  That said, you know he would have failed the save.  

Consider her Reaction void because of the second attack - Adray is unharmed, she simply run away.

Adray shouts, "Come on, more cultists," at the others and then moves into the smoke as well.  "There another secret door.  We need to find it quick..  maybe the wand?"

Fran would groan and mutter under her breath with the sudden flurry of actions that led to the cultists escape. That's exactly what she wanted to avoid. Especially considering who they're dealing with and trying to catch. With evidence. Sighing, the artificer would move forward straight ahead and begin checking for a secret door that could be much like the one she just found.

”When I was reading the fiends mind, I saw that woman.. It was very afraid of her.” Polly share with the group. 

Actually, the woman was not dressed as a cultist, though, an obvious familiarity with them did not speak in favour of her innocence. Reya, who did not see much from far behind, was sure by this time, that there are no innocent people in that place: "If the door can not be found - there is another one, back there. It's open. May be we can get to the house through it. But you are right, we might need caution." With a visible disgust she donned the black robe and covered her face with the mask.

Before leaving the secret room, Polly will go investigate the obsidian block for clues of what the woman was doing in here. 

The block looks like and altar. A bit worn stone tiles right beside also look like someone spent a lot of time standing here.

The group was silently staring at the black smoke with Reya gradually loosing her patience at the back of the room and looking at the double doors with growing longing. In a while, smoke began to dissipate, revealing the wall and, after careful examination - yet another secret door. Unfortunately, no matter what party tried, the door refused to open - is if locked or blocked from the other side. There is no visible keyhole or anything that would allow to toy with the mechanism of the door.

"Decision time.  Do we continue to search for an opening mechanism or beat at the door or head back and go through the normal doors?" He says to the others.  "I vote we keep moving.  If she locked it, then we either have to knock it down or find a different route "

Choir will try wobbling and moving the candlesticks, just in case, but is pretty much read to go. Maybe they will find the secret door from the other side.

Ordrag has spent the time experimenting with the weight and swing of Choir's hammer, and trying some combos with the pirate's scimitar, discarding the blade he took from the dead Dragon cultist. Then tucking both the hammer and scimitar under his robe, and the mask over his face, he goes to join Reya at the door.

Fran and Brutus would join Reya at the double doors in the other room.

If Polly can’t deduce anything from the obsidian block she too will go and join Reya.