There are indeed hostiles behind the door. Before you kick in the door, you hear one of the humans yell "No, that's not going to work!  You need to plug the bottom with blanke- Hey!  What the!?"   Dylan kicks the door in (which looks impressive but is not as difficult as it appears.  The door is in bad repair).  This room, like the one you just left, has six straw-filled mattresses.  As you walk in, there are two doors on the far wall.  A group of four humans and one duergar are in the process of barricading the door on the left with furniture.  

You recognize the humans as the ones from the bar that started the bar fight.  Everyone looks confused.  Take a surprise round, then roll initiative!

Syl's Initiative (for the future): 14

Sylivar isn't surprised to see the rabblerousers in the same sewers as they were, but weren't they affiliated with the Xanathar's Guild? What are they running from? Possibly the Zhentarim conflict? Perhaps it was the Stone Ranaer referred to. If the Zhentarim - or whoever - was at the door, they would certainly appreciate help in taking down the enemies here.

"Hey, you! I don't want to hurt anyone, so make any explanations you have quickly!" calls out Sylivar, before rushing towards the nearest entity, spinning a Bo Staff to the knee and following with an uppercut to the chin, once again aiming for nonfatal wounds.

Action: Quarterstaff - To Hit: 19 dealing 7 Bludgeoning damage.
Bonus Action: Unarmed Strike - To Hit: 13 dealing 4 Bludgeoning damage.

Action after the Surprise Round will change pending on response / initiative order. 

Dylan's Initiative:  15.

Dylan will rush up to the deurgar goon and try and knock him out with the basket hilt of his rapier.  This is all very strange this fighting without hurting people concept.

Move:  Get into melee with the dark dwarf.
Attack: 25 Damage: 18

Initiative: 20

Eekz hides just behind the door frame as he pops out and looses an arrow at a kneecap of a human and then quickly hides against the door frame.

"Eep! Gobbo 'as nah idea wot ter do!"

Attack: 6 Damage: 7

Sneak Attack: 3

Stealth: 23

Initiative:  3

Gil starts to rap out a tune as the fighting starts:

"Don't call it a comeback, cause I been here for years, I'm rockin my peers putting Xanthars in tears, as I'm crawlin my way through the filthy seweeers . . . 
I'm gonna knock you out, Mama said knock you out, I'm gonna knock you out, Mama said knock you out."

Bonus Action:  Bardsong to Dra'vos

Gil then fires a stone at one of the humans that hasn't been targeted yet, aiming at it's head trying to knock the sap out.

Attack:  Sling, 12, Damage on hit: 6

"So, why aren't we killing anyone again, I'm pretty sure that the feeling isn't mutual."

Move: Rushes up along his friends trying to flank as many of the baddies as he can.

Dra'vos Initiative: 3

Dra'vos speaks his words of power, makes a few simple hand gestures, and casts Ray of Frost at one of the humans that have not been hit yet.

Spell Attack: 21 Damage: 8

Initiative for Gaèl: 15

Gaèl rushes in with the rest of the group, aiming for the human Gil struck with his sling before.

Attack: 8 Damage: 11

(Well.  Dang.  haha  I should know better than to give you surprise rounds.)

Sylivar - 21

Dylan - 15

Eekz - 12

Gael - 9

Gil - 8

Dra'vos - 3

The Duergar begins to grow, to the point where his head nearly scrapes the ceiling.  However, with Syl and Dylan attacking him, he looks near to unconsciousness.  The others face similar fates.  The one Eekz attacks is pelted in the knee, and after a short scream, he falls unconscious.  The one Dra'vos strikes with ice begins to shudder and can barely move.  His core temperature has started to drop.  

Gil casts a stone at the leader of the humans, who looks more formidable than the others.  He misses entirely, the bandit nimbly dodging out of the way.   The distraction of the song and stone is, however, just enough to provide Gael an opening to attack.  Gael takes advantage of the opening, slashing at his chest.  The man attempts to parry it, but he responded just too slowly.  

The first bandit responds to Gael's attack, swinging back with his own scimitar at Gael.

Attack: 14 Damage: 7

He then fires a crossbow bolt at Gil 

Attack: 21 Damage: 6

(Syl, then Dylan, you're up)

One unconscious enemy was enough, so Syl continues to rail into the Duergar, with intent to kill.

Action: Quarterstaff Attack - to hit: 25 dealing 10 bludgeoning damage.
Bonus Action: Unarmed Strike - to hit: 8 dealing 4 bludgeoning damage.

Dylan will take his cue from the monk.  Time to switch into slice and dice mode.

If the deurgar is still up and fighting after Syl's wallops he'll try and focus that guy down.  If not, he'll prance agilely over to the leader and attempt to skewer him instead.   Either way:

Attack: 6 Damage: 8

(Ah crap, Gil should be up too, initiative 18.  Sorry)

"Hey!  I am not a freaking pincushion," 

Gil switches to his Rapier / Dagger combination as he's flanked the leader and gives him a little pokey pokey.

Attack Rapier:  20 Damage on hit: 5

Bonus Action, Attack Dagger:  23  Damage on Hit:  4

(I was supposed to roll the Bandit's crossbow bolt at disadvantage, so here that is.  12  That still hits)

Syl, your first strike misses entirely, but your second smashes the duergar in the sternum.  he stops growing and falls over wheezing with decreasing rapidity.

The flurry of daggers catches the bandit that Gil is attacking, leaving him with open wounds.  The other bandits cower, seeing the two more accomplished fighters so easily manhandled.  Their own injuries humble them too.  They drop their weapons, hands up. The bandit leader says, "You fools, fight!"  

Renaer speaks up, "Yes... fight.  I'd love to deliver some pay back."  He then takes two of the daggers he'd picked up and throws them at the bandit leader.  

Attack: 10 Damage: 5

Attack: 14 Damage: 7

 Gael, Dra'vos, you're up.  The common thugs have disarmed, but the bandit leader is still fighting.  He's losing blood fast though.  

In an attempt to end the fight as fast as possible, Gaèl strikes again with the intent to disarm the bandits leader in whatever way may seem most convenient - regardsless of whether he accomplishes this by slashing away his weapon or by relieving him of the hand holding it.

Attack: 19 Damage: 5

"You are a brave man," Dra'vos comments to the bandit leader. "A fool but a brave one at least."

Dra'vos raises his hand and speaks the arcane words to cast Fire Bolt at the bandit leader.

Attack: 18 Damage: 3

(Well, I was going to drag this out more, but I just found out that I'm going on mission for a couple weeks starting next monday.  I won't have internet access.  Sorry about the couple day's delay!)

Gael, you disarm him indeed. His hand falls to the ground, along with the shortsword he was carrying.  He yells out, "STOP" and willingly drops his crossbow.  

"Where is my friend, you foul creature?" Renaer holds his rapier at the bandit's throat.  His usually calm and diplomatic demeanor has evaporated into a focused rage.  The bandit seems too stunned to respond, in light of the violence following his surrender.

Gaèl glances at Raenor, clearly surprised, then turns to the bandit. Stepping a bit closer, he holds up his hand right next to his ear and does a loud flip. "Speak!" , he rumbles, a pressing tone in his voice. "With every second you waste, you'll be closer to bleeding out. Talk now - we patch you up to live another day."

Sylivar nods at Gael's handling of the bandit before assuming a position near the outcropping of a door. He wasn't the best at interrogation, but he certainly can perceive and prevent a threat from approaching. He wonders what the bandits were barring the room for.

Gil nods, "Yeah, let's keep an eye on him, I have a feeling we may be holed up in here for a while."

Eekz slowly appears in the bandit's peripheral vision, nose touching nose and a small hand slowly and very carefully pokes the bandit in the cheek. A very wide Goblin grin appears on Eekz's face.