Terminal Provocations

The Cerritos finds itself in a standoff with the Drookmani over the salvage of an old Starfleet ship. Mariner and Boimler's friend, Ensign Fletcher, offers to recalibrate the ship's isolinear cores for them so the two can leave work early to attend a concert. They return to find him the victim of an attack and the shield core missing. Rutherford shows off his new holographic assistant to Tendi in the holodeck: an anthropomorphic Starfleet badge named Badgey. The Drookmani attack the Cerritos, which is without shields due to the missing core, causing a holodeck malfunction that results in Badgey becoming homicidal. Badgey attacks Rutherford and Tendi, who defeat him by changing the holodeck program to a tundra which freezes Badgey. Boimler and Mariner discover that Fletcher staged the attack because he was unable to complete the work.

Summary from Wikipedia, CC BY-SA 4.0.