The FBI's investigation into Nate's murder has been suspended. Michael wants to continue the hunt for Nate's killer himself, but he'll need the FBI's file of compiled evidence first. Sam introduces Michael to a desperate federal agent who's willing to hand the file over in exchange for help finding a notorious gangster.
Meanwhile, Jesse and Agent Pearce identify the gun that was used to murder Nate. If they get their hands on a list of everyone who's purchased the gun over the last 12 months, they might be able to learn the killer's name. The manufacturer is unwilling to part with that information, so Jesse and Pearce have to blackmail him.