Deeks goes undercover to keep tabs on Monica Gatlin, who was the target of an assassination attempt in Downtown LA. As Hetty briefs the rest of the team, they learn that Monica stole diamonds from Johannes Aardt, a former arms dealer turned successful club owner, and they need to determine why Aardt was in possession of those diamonds in the first place. Kensi goes to keep tabs on Deeks and Monica, while Callen and Sam stake out Aardt's club. They locate and arrest Pieter Brakel, the man who tried to kill Monica, and interrogate him for information. Brakel tells them that Aardt was acting as a broker for a deal between an unknown buyer and Isaak Sidorov, the international arms dealer in possession of stolen nuclear weapons. Monica gets the drop on Deeks and Kensi and escapes with the diamonds, but they eventually corner her and convince her to help them in a sting to snare Aardt and, potentially, the buyer. The deal goes south and both Aardt and Monica get shot, but they live and the team takes them into custody.