Callen and Sam join forces with Anna Kolcheck and the Bureau of Alcohol, Tobacco and Firearms (ATF) when Arkady Kolcheck warns NCIS that a notorious international weapons dealer has returned to the states. Also, the case requires Eric to go undercover as a bank IT technician.

Callen, Sam and Nell travel to the Angeles Forest to search for pieces of a failed rocket launch, including a top-secret government device. Also, Hetty tries to help Keane acclimate to life in the states.