Rangel motions to the party to follow him around the bend in the sewer up ahead and even though you know it's guarded, the sentries must be well concealed. These are some serious professionals—you can't spot any of them. He holds up a hand to bring you to a halt while closely examining the wall, looking for something.
A single splash echoes behind you. Rangel quickly spins around towards the noise, crossbow in hand.
"Oh, Marco, it's you. How did you follow me for so long?"
Marco points at a ring as a big smile creeps onto his face. "New toy. Watch." Marco vanishes, or at least his smile does—it's hard to tell in the dark. The grin reappears, bigger this time and a foot to the left. "One of those Staffers was following me. Doubled back on him and picked his pocket. He must've just confiscated it. Must be 'cursed'," Marco says, chuckling as the last word comes out. "Anyway, hand me your copper."
Rangel fishes about the pouch on his belt, his fingers carefully feeling each coin. A few moments later, he procures a single copper piece, slightly worn and unremarkable. He holds it up between his two fingers and carefully feels the surface.
"Here ya go, Marco," Rangel says, handing the coin over.
Marco replies, "We'll see. Where is my coin? Ah, here."
Marco puts the two coins together casually, matching the fronts together. Adjusting them slightly, he raises them up, holding each in the small amount of illumination that creeps into the tunnel.
"Satisfied, Marco?", says Rangel, holding out his palm, expecting the return of his coin.
Marco nods and places the coin back in his hand. "Follow me," he says, touching a brick on the sewer wall, opening up a small, hidden door. "There's a small stash back here that we need to identify and fence. You", pointing at the yourself and your companions, "you can help us identify this batch, right?"
Fortunately upon arrival in Nyamo and the difficult delivery of the alligotonium, the Order of the Staff gave you a scribe orb. It's fitting that you should use this item to help their enemies. You nod and begin to enter the small room.
"Wait," says Marco. He puts his arm across the doorway, blocking the entrance, then reaches up behind the door. An audible click is heard as a trap is presumably disarmed. "Ok, now you can go in." He notices Rangel's glare. "Hey, it's just business. It's disarmed now, nothing to worry about."
"All right. Identify these. Let me know if there's something cursed or weird about them. We can't be fencing inferior merchandise now, can we?"
You pull out the scribe orb and begin to identify the first item, a small dagger, while Rangel collects up a few small bags of coins. As the orb's power begins to analyze the weapons enchantment, recording it on a piece of parchment, Marco knocks the orb out of your hand.
"Where did you get that!? Do you realize what you've done?", he says, backing up to the entrance and clicking the trap back into place. "Explain. Quickly. We have mere minutes before the Order is here, courtesy of that orb you are using."
Seeing your confused expressions, Rangel jumps in. "Marco, what do you mean? These guys are good, we can trust them, they could have betrayed us at anytime, what's going on?"
"Rangel, that orb. That's a trap! Anything identified with that orb is transmitted to the Order: they know exactly where and what we have—we don't have time to discuss this! Leave the items here. Rangel, come with me. You," he says, pointing at the party, "stay here. The trap here will make sure you stay, so you might want to stay away from it. Of course once the Order arrives, it could take care of them instead. You have a choice to make, here and now: that trap just might take care of our problem, or it may not. In any case, the Order will be here soon, and that will be YOUR problem. I suggest you destroy that damn orb too, no matter what you do."
With that last piece of advice, Marco yanks Rangel out of the room and darkness falls as he closes the door.