Sekkar, Zeno and Rhayna agree to go and look for the mysterious derro seen in the bazaar. As they head up the stairs, Sarith runs to join them, saying he wants to see more of the duergar city. With the bazaar closing up for the day there are less people thronging the streets, but they are conscious that the ever-watchful Stone Guard could be anywhere invisibly watching. Making their way back toward the market, among the constant clanging of the forges, another sound is heard, followed by a sight most frightening.

A heavy whooshing of air grows louder, and turning to see the source of the sound, through the thick smoke and shimmering heat haze, the four travellers see a huge red dragon circling the city. It lands on one of the buildings not too far away, and breathes fire down through a chimney-like structure, before lifting off and flying to the next building. Incredibly, none of the local seem to pay it more than the most casual glance, suggesting that this dragon is a known and regular feature in the city, and seems to be maintaining the forge fires throughout the city. At one point it lands on a building very nearby, and after breathing fire down another chimney, the dragon appears to look directly at the four watchers. But a moment later it lifts off again and flies deeper into the city.

Searching through the market area, no certain trace can be seen of the derro, which is not surprising given the crowds that were here earlier. The last Rhayna saw of the creature, it was nearer to the docks, so they decide to search more in that direction. Unlike surface docks, the boats on shore of the underground lake don't bob up and down from wind and wave, but sit stationary on the surface of the dead-calm lake. The docks seems to be currently vacant save for a single male duergar standing at the end of a pier a short distance away (about 100 feet).

Suddenly, two duergar appear beside him and start to stab him viciously with glowing swords. The assassin's faces are masked and hooded.

Kastix, Kaylyn and Joetaro bid the others take care as they decide to remain at the inn. The same patrons are seen as before, now including the two hobgoblins who keep to themselves in the corner. Some of the deep gnomes are new, and others from the night before are now absent. The lone drow remains in the corner, watching all the others. The three travellers either keep to themselves in the dining room (cave) or retire to their rooms.

After about an hour, a small commotion is heard in the entry-room where the clerk sits. Six duergar have arrived and speak with the voice of authority to the clerk, then make their way through the inn. Most of the other 'outsiders' seem to know something of them, as they hush their voices and look down at their plates and cups, trying not to meet the gaze of the duergar. They appear to be some form of cleric, carrying maces and hammers, and wearing chain armour and cloaks fastened with a mithril pin depicting an arrow breaking on a shield.

The clerics appear to know exactly who they are searching for, and spread through the inn until they locate Kastix, Kaylyn and Joetaro, demanding that they come with them. Like most duergar in normal circumstances, they look like they mean business, but these ones in particular have an aura of authority and seem accustomed to being obeyed. After a thorough search of the inn, one of the cleric asks in Undercommon: Where are the other four?

(Oops - I thought at least one of you understood Undercommon)...

Seeing that neither of the three appear to understand his question, the cleric repeats it in Draconic. Kde sú ďalšie štyri? 

Sarith agrees whole-heartedly that they should avoid becoming involved in local matters. Sekkar moves stealthily forwards, with Zeno, Rhayna and Sarith following. It is scarcely necessary to tread lightly with the constant hammerfalls echoing constantly through the city, but they try to keep hidden behind dockside boxes and mechanical lifts, staying within the shadows cast by the red glare from the city forges. It is easy to see the glowing swords of the bandits as they finish their grisly task, and the victim's body slumps to the pier. As the three try to draw closer, the sound of heavy boots can be heard going past, running toward the scene of the murder, although no figures can be seen. The bandits look up from their prey and turn sharply, appearing to have heard the footsteps also, and they suddenly vanish from sight. A moment later several duergar guards appear out of thin air, running toward the pier, and they fan out in an attempt to apprehend their invisible quarry.

All three make a Stealth check (Rhayna with disadvantage), and also a Perception check, all with disadvantage.

Sarith: Stealth: 10 Perception: 11

The duergar cleric spokesman turns to Kaylyn, and gives her a look that although still stony with authority seems also a little less threatening than before. We are the Keepers of the Flame, he says. Our leader, Gartokkar Xundorn, has noted your presence in the city, and has summoned you to appear before him. You are not accused of anything at this time. If your companions are not present, then you will accompany us for now.

You can make an Insight check if you want to try to read his intentions.

Although Kastix can't actually understand the duergar cleric's words, he reads in his face that his intent is non-hostile. It's just typical duergar stoicism, pragmatism and contempt for all non-duergar races.