When an NCIS agent turns up dead and Kasie goes unaccounted for, the team must work quickly to find the killer.

Parker and Knight discover three bodies on an old Navy ship that's about to be sunk and turned into an artificial reef, when they're suddenly locked inside by a mysterious figure. Also, Vance offers Knight a unique opportunity.

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