Callen and Sam fly to Idaho and join forces with NCIS: Red, a mobile team of agents who live together and investigate crimes in various locations, when a murder weapon found there matches one used in a national security case in Los Angeles.

While the LA team chases leads digitally and locally, the NCIS: Red team travels in their mobile trucks, nicknamed "Laverne and Shirley", in a race to track down a cunning terrorist before he disappears.