I have a rundown of the epesode couresy of the X-Files web site. Several heavily-armed crack dealers receive an anonymous telephone call alerting them to the whereabouts of a hated enemy. The men all converge on a diner, but none find their target. Two deputy marshals receive a similar anonymous tip, alerting them about a Colombian fugitive in the same diner. The marshals enter the diner and order everyone onto the floor.
Drug dealers draw their weapons and a fierce gun battle ensues.
Gelman had been working at his laptop inside the diner when the shooting broke out and became trapped in the cross-fire. Mulder sneaks Gelman's laptop under his jacket and brings it back to Scully's car. He finds a blank CD in the laptop drive, which when placed inside Scully's CD-player emits music from The Platters' Twilight Time. Puzzled, Mulder brings the CD to the Lone Gunmen for further analysis. When they are unable to crack the disc's security code, Scully suggests they check Gelman's e-mail log.