(( Sterling's Intelligence Check: 3 ))

"Who in the world is Xanathar?" asked Sterling in exasperation as Wagner began searching. Shaking his head, he moved to follow after.

Wagner moves the tarpaulin aside to see what's beneath it.

Casz will take the time to search the corpses of the men, as well as the fallen kenku. He's mostly looking for money, gems, information -- little things, really.

[Investigation: 9]

“We know that Xanathar and the Zhentarim are at odds. If we can assume that the pretty boy is the one we are looking for, then he was taken hostage by the Zhentarim and has been stolen by Xanathar. Sounds like we’re in for a tour through the sewers,” Oriace comments while helping to search he room, specifically if there is anything that might have been left behind from the prisoners, like clothes or other belonging, but also helping the others. (Investigation: 10)

Under the tarpaulin is a man, currently unarmed but otherwise looks like the image in the spoiler. 

 He pulls back as you uncover him and looks visibly terrified.

Those searching find a total of 5gp, 4sp and 13cp across the various corpses. There is weapons around (rapiers, daggers, light crossbows+bolts and a couple of shortswords). That is it for downstairs.

Assuming someone has a way to open the crates in the secret room (crowbar would be best. Other methods are available), the contents are in the below spoiler.

"Hey, its okay, were here to rescue you.  I'm Wagner, what's your name, friend?" Persuasion: 18

"Finally! Someone who doesn't know me and therefore doesn't judge me on sight. I am Renaer Neverember, unfortunately the son of Dagult Neverember" the man replies with grace and articulation giving away his noble heritage. "Wait, you aren't with the Zhent's or Xanathar are you? Oh who am I kidding, you wouldn't have stopped to talk if you were."

"Wagner, sword-dancer extraordinaire at your service. Do you know ought of the missing Floon we seek?" Wagner says to Renaer.

To the others he shouts, "Guys, we've got a noble here, but not the guy we were sent to find!"

Oriace approaches the noble with a respectful bow, his deep voice resonating with confidence yet humble in tone: "Good evening, my lord. I am Oriace, a humble bard with a gift for storytelling and a deep connection to the rhythms of the drum. It would be a great privilege to entertain you at the Yawning Portal, should you find it pleasing." Oriace grimaces somewhat during the bow as his fresh wound doesn't agree with the movement. "Now, if you don't mind, I'll sit here a moment while we plan on how we can find your acquaintance, Floon Blagmaar. You wouldn't know what has happened to him, would you? Or at any rate, could you tell us how you've got here?"

Sterling followed the others in. Upon hearing Wagner and looking over the man, he did his best to hide his disappointment. "Well, at least we managed to save someone," he thought as he forced a friendly smile onto his face.

Quote from cyreon >>

"Now, if you don't mind, I'll sit here a moment while we plan on how we can find your acquaintance, Floon Blagmaar. You wouldn't know what has happened to him, would you? Or at any rate, could you tell us how you've got here?"

The bard raised an eyebrow at the question. Indeed--what exactly was going on here? Was someone trying to kidnap and ransom as many nobles as they could before fleeing the region? He watched the man carefully as he awaited his answers.

Casz strolls in as well, though his is more subdued, a man more than used to hiding his... disapproval.

He leans against a nearby wall and waits to hear this nobleman's excuses, with baited breath.

[Would you rather I used passive insight (15) or rolled insight (11) for this?]

(I will allow passive here, he seems to be truthful with everything he is saying, and when Floon is mentioned, looks genuinely sorry/upset/guilty)

"I do know Floon well, he is one of my close friends. I didn't allow Floon to head home by himself as he was far too intoxicated so I offered to escort him. We were then ambushed by 5 Zhentarim thugs, all of which I see dead here. The Zhentarim thinks that my father embezzled a large amount of gold while he was Open Lord, and that he hid the dragons somewhere in the city. They think they can find it by using an artefact called the Stone of Golorr, which was in the hands of the Xanathar Guild until recently. Apparently, someone stole it. The Zhents thought I knew something about all of this, but I don’t. My father and I haven’t spoken in years. Just as they were starting the interrogation, the Xanathar thugs broke in. I was able to get free of my bonds and hide, but Floon wasn't so lucky. I believe they mistook him for me and took him with them, likely with the aim to interrogate him the same way the Zhent's planned with me"

Sterling's eyes widened as he rushed towards the noble. "They took him?? How long ago was this?!" he asked, the urgency of the question coming through without concealment.

"Thank you, Sir. I fear that you are right and your friend is in danger. In mortal danger when it becomes clear that he isn't, in fact, you." Oriace turns to the others, "I would argue that we should hurry after them, but I feel rather drained (Oriace is at 3/10 HP) and I could use a short rest here before continuing."

"It was hard to tell time while hiding in a dark room as they left some people behind in case more Zhent's turned up. Its been some hours though I think."

“If they have a few hours on us already, then, I think, we can rest an hour. It won’t change much, right?” Rumbles Oriace with a pained grimace. 

"Fine by me." Casz stretches, having done nothing but flirt, drink, and steal since leaving their last gig. He could use a break. He wonders if the gnome and dragonborn are still back at that dive joint.

"I could use a breather and to tend my wounds a bit." says Wagner, "I'm not at my top form."

Wagner with also speak to Renaer, "Neverember, are you willing to fight with us to rescue your friend? I don't think we have time to escort you out of this area safely and these are rough streets to travel alone."