When a trio of combat vets are found murdered in a D.C. motel room, NCIS tracks down a suspect who refuses to talk to anyone but Sam Hanna.

As NCIS investigates a dangerous connection between the Nexus cartel and Parker's longtime nemesis, mob boss Carla Marino, the team uncovers a high-stakes plot involving stolen nuclear material. With time running out, Parker is forced into an uneasy alliance that could determine the fate of the operation - and his own future.