You received this earpiece from Agent Nance as a 'memento' of working together, though you're fairly sure he wants to try to spy on you with it. Regardless, it reminds you of an adventure you call...
It all started when a man named Keith Nance accused you of being a murderous villain. You tried to prove your innocence to him, only to be interrupted by news that you were attacking the Faultline Dam. Despite not trusting you, Nance agreed to work together with you to get to the bottom of this. You went to the Faultline Dam and saved the Dam - and a Wyvern agent - from the Freakshow. However, your evil double was not there. Nance called in to you, saying that your double was spotted by Agent G. It also seemed that Nance was starting to trust you...somewhat.
You spoke with Agent G, who pointed you towards an Arachnos base within Faultline. You arrived to find the base engulfed in flames! Your other self had been through here, though for what reason you did not know. You hacked an Arachnos computer to discover that the base was being used as a monitoring station by Arachnos. Shortly afterwards, you were attacked - by your mirror! You defeated them only to realize that this couldn't have been the evil you. Nance informed you that the evil you just tried to attack Mirror Spirit. The version of yourself that was defeated was taken into S.A.M. custody while you went to speak with Mirror Spirit.
Mirror Spirit knew at once that you were not the evil clone and told you where your evil self went. You traveled through the sewers of Faultline and fought your evil self. However, much like yourself, your evil double was connected to a medi-port system!
You received help from Nance and Citadel to track down where your evil double went, though Nance informed you that your other double escaped S.A.M. custody. You busted into your evil double's base to discover your good double there. The two of you split up - you went after your evil self, while your double went to save Agent Jenni Adair, who had been kidnapped. You fought and defeated your evil self, but could not ask it any questions. Moments after being defeated, your evil self died, most likely from some internal device.
You returned to Keith, who thanked you for your help, but noted that the investigation wasn't over yet, not when you discovered your clone was working for someone else. While you were able to clear your good name, this would only be the beginning of your work with the S.A.M....