After interacting with the second thief, return to the save point and teleport back to the thieves' camp.
After teleporting back, ignore the third thief for now and take the other path. First, climb over the wall to grab the purple item.
After obtaining the item, open the door on the right. Inside is Quick-Fingered Zhang's hideout.
After talking to Zhang, you'll receive the offensive accessory "Quick Fingers in Hand."
