After tracking Apollyon, a deadly underground spy network, to war-torn South Ossetia, Pride is separated from the team and faces grave danger. Also, in order to save Pride, the NCIS team must locate a mole who continues to feed information to Apollyon.

Pride must cut his vacation short when Hannah is suspended for breaking protocol during a joint investigation with the FBI.

Tammy must protect Rachel, a research-obsessed teenage girl, after her father is shot in their home, while the rest of the team searches for a motive.

As Pride directs the team to link Sasha to the recent attacks in New Orleans, he must help Connor come to terms with who his mother really is. Also, Carter and Tammy search for a stolen highly trained military dog, and Pride and Rita make an important decision about their wedding.

While Pride and Rita plan their wedding, the FBI arrests Connor in connection to the bar's firebombing as a means of getting to his mother, Sasha Broussard, and Rita may be the only person who can save them.

On the eve of his wedding to Rita, and Connor leaving for the Witness Protection Program, Pride must track down who attacked Jimmy and Connor, while navigating Sasha's ulterior motives regarding her son.