Two gunmen steal the body of a Muslim man, Yusef Afzal, from the morgue after he was murdered in his home. A classified Navy signature embedded in a type of residue is found on Yusef's body by the coroner before the body is taken. NCIS:LA is called in to find Yusef's killers and their connection to the mystery residue. Eric traces the residue to a classified Naval program that was developed to tag and track terrorists. A former Homeland Security employee, Hector Lee, who worked on the project was found to have been tagging young Muslim men in the L.A area to track them because he believed they all were a risk to national security. Yusef was one of those men and once Eric unlocked the Hector's encryption, the team located Yusef's body but was shocked to find it was on the move in the hospital he worked at. Sam and Callen rush to the hospital to find Yusef's decapitated head near a secured access door where nuclear pharmaceuticals had been stolen. The team uses nuclear tracking devices around the city to trace the men's whereabouts. Sam and Callen find one of the killers and shoot him dead as they find the nuclear material in his bag. Deeks chases down and fights off the other killer who Deeks shots dead as well. The men intended to sell the nuclear material to terrorists who wanted to make a dirty bomb. Yusef happened to be a technician at the hospital who the killers targeted because they saw he had access to the area they needed to infiltrate and they killed him at his home but needed to then steal his body morgue after a neighbor heard the commotion and came to the house interrupting the killers plans.