Cause some chaos and get the town guard

As the two of you walk, you gently talk between you; eventually the conclusion becomes that you simply can't do anything by yourselves with the two bodyguards there. As such, as you examine the people on sale — you still can't help but to have your stomach turn at the thought — to avoid suspicion, you two start quietly plotting.

"So, what kind of help do we need?"
"We could always go get Giovanni and Aaron but that would require coming back another day. I don't want to let this continue longer than it has to."
"What about the town guard?"
"…"
"…"
"Yeah, I suppose they'll have to do."
"One of us is going to need to contact them, which means we're going to need a distraction."
"I don't have the best rapport with the guard, and I can create a distraction, but I'm going to need the bodyguards' attention off me first."

And so, you head towards the bodyguards. They seem well-trained, so run-of-the-mill distractions are much less likely to work, especially since you have a feeling that that's the sort of distraction which Irina will be making. You reach the bodyguards at the door, and do your best to flirt with them, pushing down the revulsion of dealing with slavers. "So, how much to buy one of you?" "Ma'am, we're not for sale." "What about just for the night then? Surely your employers don't pay you so much that you can't use a bit extra." "We're actually the owners." Oh. You blink in surprise, but continue undeterred. "Well, surely you can relax for a bit and release a bit of stress then." They hesitate, but do end up taking the bait, with flirty banter going back and forth for a few minutes, until eventually they agree to bring you to a private room. However,

"DOWN WITH TYRANTS! DOWN WITH SLAVERS!" comes a voice from up above, causing you to crane your head towards Irina, who is up on one of the chandeliers. Just how did she even get up there? Never mind that, this is just about the perfect distraction to allow you to slip away, as papayas start raining down from the ceiling and people start scrambling to get away from the falling fruit (where did she even get all those papayas from?). The two bodyguards turn to you, "we'll take a raincheck on that - we need to deal with this. Should be resolved within a couple of hours." You nod, fleeing down the hall with a couple of other people. And once outside and out of sight, you book it to the nearest guard post: after all, you were just given a pretty strict time limit on when Irina will run out of time.

About half an hour later, you arrive at a guard post, probably about thirty guards inside. You hurriedly explain the situation: about the slavers, about the auction underground, about Irina, about the people enslaved. This gets their attention at least. "Miss, I didn't quite catch all of that, but I caught enough to know that it's serious. Lead the way and we'll perform some arrests." And so you wind up leading a squadron of two dozen guards, leaving a token **** to maintain the post itself, to the house. The guards wait in the alley, while you go up the stairs. Knock knock knock. After about five minutes, you hear from the other side of the door, "password?" "A bird in two hands." The door opens, and you step in, "is that chaotic situation resolved?" "Yes, I do believe so. They should be capturing her about now." "Ah, very good." Thankfully, your idle chatter bought enough time for the guard to start streaming in through the door, flooding the hall past you as armored boots clank down the hall. You follow, and what proceeds is honestly a mopping up: there's only approximately five who are combat-capable on the other side, and though any one guard member is individually weaker than even the weakest enemy combatant, they simply can't compete against twenty four guards, one adventurer, and an additional formerly subdued paladin once one of the guards unties her.

Once combat is over and the enemy subdued, the losses are tallied while some guards perform arrests (especially of the two bodyguards, who you inform the town guard to be the owners) and yet others start tending to the various formerly enslaved people on display. The tally ends up such that seven guards were seriously injured, two were killed, and one of the simple thugs was unable to be subdued non-lethally. No non-combatants were injured, but two were able to escape entirely: one "customer," and the concierge who answers the door.

"Ma'ams, I do apologize, but I am going to need to ask the two of you to assist further. We're going to need testimony so we can figure out which crimes to charge them with, and we're additionally going to need to ask you to witness in the trials."

Hells. You just wanted to set the slaves free; you didn't want to get wrapped up in all the legal shenanigans to follow. Oh well, no real avoiding it now you guess.