As the NCIS:LA team investigates the deaths of two men with ties to a local gun shop, they soon learn that one of their own agents could be at risk. Ops informs the team that Agent Mike Renko is in the midst of an undercover operation at the gun shop in question, and that these two murders put his cover at risk. Callen, Sam, Kensi, and Deeks go to the gun shop to extract Renko, which they eventually do after a gunfight with the proprietors. In the aftermath, Renko thanks the team, then takes a bullet through the jaw from an unseen sniper. Renko survives the surgery to remove the bullet, but then dies after going into cardiac arrest in the hospital. Sam and Callen try to track down another employee at the gun shop, but they find him dead in his hotel room, also killed by a sniper's bullet to the jaw. As the team tries to piece together the killings to get a better idea of the person behind it, they get news that a location has been set for an arms deal that the gun shop owners were organizing. The team poses as the shop owners at the deal, but they're surprised when the people they meet turn out to be a college moving crew. The kids tell Callen and Sam that their driver was the one who organized everything, so they try to track him down on security camera feeds. When Nell tells Callen that the driver hid just out of sight of the cameras, Callen has a scary realization: the driver is none other than The Chameleon (Epis 315), the crafty criminal who promised to get revenge on him. Eric finds the Chameleon's location via GPS and the team races off to catch him, wary of what might be in store for them. When they arrive, The Chameleon tells Callen he needs to take a call, but it turns out the phone he answers is wired to a car bomb -- and NCIS Agent Lauren Hunter is bound to the steering wheel inside the car. With a smug smile, The Chameleon detonates the bomb, incinerating the car, and then drops to his hands and knees in surrender.