Nightwielder immediately turns to face me, but I pretended that he is focused on making the device work and not aware of the Epic. David had activated the recording function of the device and conceals and removes the data chip containing the recording. David then pretends to notice Nightwielder watching him for the first time. Nightwielder destroys the scanner but leaves David unscathed, and David says he will return to the back of the store to continue inventory. He finds the newly dug tunnel, joining Abraham and Megan, and explains about selling Abraham's gun. They travel through the tunnels before stopping to verify they aren't being followed. David plays the video from the recording chip, showing Nightwielder become corporeal from exposure to the UV light, which impresses Abraham greatly but angers Megan due to the risk.

-Summary
http://coppermind.net/wiki/Steelheart/Summary#Chapter_1