Billy was the night watchman at the Southwest Aniline chemical plant.
Billy was making his rounds in a golf cart when he stopped to use the restroom. He radioed this into his fellow guard, Jimmy, who sarcastically wished him luck. After Billy entered a porta-john, both Walter White and Jesse Pinkman snuck up and tied a cable around the stall to prevent Billy from coming upon their theft of the methylamine. After the alarm to the warehouse went off, Billy tried to leave the stall, but was unable to do so thanks to the cable. As Walt and Jesse stole a barrel of methalymine, Jimmy radioed in to ask Billy about the disturbance, but Billy was only able to yell out from the stall while Walt and Jesse escaped ("A No-Rough-Stuff-Type Deal").