Gibbs and McGee travel to Russia to safely escort home an NCIS computer engineer connected to classified intel, but their mission is compromised and they are forced to go off the grid while hunted by a Russian mercenary group.
After the passengers and crew of a private plane travelling from New Orleans to Washington, DC, are lethally poisoned, all evidence points to the missing chef, Abby's brother, Luca.
The NCIS team suspect Gibbs' arch-nemesis is behind an explosion, but Gibbs elects to sit out the investigation in order to help a grief-stricken Fornell, whose life is on the verge of imploding following his wife's murder.
The Secretary of the Navy assigns the NCIS team to a joint terrorism task force after a naval research scientist is murdered and the lead suspect is wanted by the Russian government.
With the authorities closing in on Philip, the Jennings family must come together and make a life-changing choice about their future.
