Three of the guards are gathered around the body, while three others are searching the area. Zeno, Rhayna and Sarith can't quite hear the guards conversation over the background noise, but Sekkar hears snatches of their conversation (which in any case is in Dwarvish): fear eile ... Taibhsean Liath ... malairtiche ... aon làmh a dhìth ... ràinig e an-dè ... Just then one of the guards points in the groups direction, and his next words are easy for Sekkar to hear: Drow! Air cùlaibh an gantry sin! Cuir an grèim e! and all but one of the guards come running toward the group.

(Sarith' Stealth score letting the team down)

Translation: "another one ... Gray Ghosts ... trader ... one hand missing ... arrived yesterday ...

Drow! Behind that gantry! Arrest him!

Joetaro can't read their intent from their expression, but Kaylyn's opinion is the same as Kastix - these duergar are not hostile and don't appear to be 'arresting' the characters, but rather issuing a summons from a higher authority. Even so, they also look like they expect to be obeyed, and probably wouldn't take kindly to a negative response...

I think there was a confusion here: neither Sekkar, not, I think, Zeno, planned to sneak out on the assassins, only to follow them after they were done. I thought this is what we were doing, not coming closer to the crime scene. Sekkar even said as much - not to interfere and stay away to not be framed.

Yes, I understood it as such. They were in hiding so as to not be seen by the assassins, but were waiting for them to finish so they could pursue them. However, they never had the opportunity to pursue the assassins. The guards approached the scene while the murder was taking place, and the assassins promptly vanished. Then the guards spotted Sarith, even though none of the party were any closer to the crime scene than before.

The duergar priests escort Kaylyn, Kastix and Joetaro out of the inn and through the gates separating the Darklake district from the rest of the city. The buildings are just as unadorned as the ones near the lake, built simply for purpose and nothing else, in many ways like the duergar themselves. Many give the group suspicious looks as they pass, but they go dutifully about their labors with stone-cold efficiency. As one point, the group cross a bridge, one of many that span a wide rift in the ground that seems to divide the city into northern and southern districts.

The escort takes the group to the far south-eastern corner of the mighty cavern, and toward a building carved from the stone beside the entrance to a very large tunnel. Another cleric stands waiting in the doorway, and the escort salutes him. He is about to speak when suddenly the ground trembles slightly, and a thunderous voice echoes against every wall.

Gartokkar, the voice calls as a reptilian behemoth comes into view, its scales the color of lava, its bright yellow eyes glowing in the shadows of the before coming into the light. You didn't say I was having surfacers for dinner today. The dragon chuckles at his own wit. His massive body gives the distinct impression that he is overweight, indicating eating habits that don't bode well.

Foreigners, the duergar high-priest says with great reverence, meet the Father of Flame, the Everburning, and the Foundry's Heart - Themberchaud, the Wyrmsmith of Gracklstugh.

Without waiting for a response, the dragon speaks again: Gartokkar, I will speak with the surfacers in private, after which he turns and ambles back into his lair. The high priest does not look happy about this, but seems to have no choice but to acquiesce, and he nods to the escort to 'prompt' the group (with a not-so-gentle nudge from their weapons) to follow the dragon. The booming voice from inside rumbles: And I mean in private, Gartokkar. Any invisible lurkers will be turned to ash.

As the group enter the cavern, they see Themberchaud making himself comfortable atop a mountain of gold and silver. Turning to stare at them with his yellow eyes, he rumbles: Now, tell me about yourselves, surface-dwellers. What are your names? Where are you from? How is it that you find yourselves in the Underdark, and what brings you to Gracklstugh?

Four, you say? Which way did they go? responds the guard in Undercommon, and directs two of the others in the direction indicated. What about this drow then? Is he with you? We'll need you to provide a statement of witness. Captain Blackskull will be here shortly. The guards appear to accept the word of the dragonborn, but retain their typical disdain of outsiders, as well as their strict adherence to order and process.

For now Rhayna and Zeno remain hidden, unless they choose otherwise.

Sarith gets the hint from Sekkar, and slinks away. The guard seems to accept the word of the red dragonborn, and makes no attempt to apprehend him. As Rhayna approaches, the guard looks at her with undisguised disdain and says: No libraries in this quarter, human. Now keep your distance! This is business of the Stone Guard. Turning back to Sekkar, the guard continues: The victim hasn't been identified yet, but it shouldn't be too difficult - he's missing a hand. Ah, here's the Captain now.

A well-armoured female duergar approaches and the guard salutes. Captain! There's been another murder. This dragonkin witnessed the incident. The captain grumbles: Thank you Gorlak, turns to Sekkar, giving him a similar look of respect, and says: Let's hear it, then. What did you see?

Sekkar, make a Persuasion or Deception check, depending on which track you choose to take when replying.

Themberchaud listens attentively to each account, expressing curiosity about the surface world, and particularly at the mention of Selune how he has never seen the moon but would like to. After the brief interview, Themberchaud speaks half to the group and half to himself as he says: Hrmmm. So you have no ties to this place. You are part of no faction. Good. You will serve my needs well. 

Themberchaud lowers his reptilian head uncomfortably close to the group, close enough that the smell of his sulphurous breath burns the back of the throat. In a voice as low as an adult dragon can speak, he says: Something here is amiss. I have sensed it for years now. These duergar who attend me - they are withholding something from me. I want to know what it is they are hiding. Long have I watched, but I am limited. I need others to go where I cannot, to be my eyes and ears. I see Gartokkar has taken an interest in you, I know not for what purpose, but I will subvert his plans. I make you my agents here in Gracklstugh. For that you shall have my protection. Your first task is to do whatever Gartokkar instructs of you, but you are to report to me before reporting to him. That is all.

The dragon then withdraws his head and slumps back into his mountain of gold, saying nothing further.