Gibbs starts his career as a newly minted special agent at the fledgling NCIS Camp Pendleton office, where he forges his place on a gritty ragtag team led by NCIS legend Mike Franks.

Gibbs and the gritty ragtag team continue their investigation at the fledgling NCIS Camp Pendleton office.

A murder near Camp Pendleton leads Gibbs and the team to a suburban mall in San Diego, where Gibbs takes matters into his own hands. Franks receives an unexpected visit.

Still grieving the loss of his wife and daughter, Gibbs helps the team work a case involving a missing girl. Meanwhile, Franks finds himself at odds with a team member, Lala's personal life meets work, and the moment that irrevocably changed Gibbs' life is revealed.

With the countdown on to an execution, Franks races to extricate the location of a missing body from a death row inmate and honor a promise he made to the victim's sister before time runs out.

Gibbs goes under cover for the first time with Lala as NIS works the case of a dead Navy seaman who may have been sharing top-secret intel that poses a threat to national security; Lala struggles with an unexpected development in her personal life.

As Leroy Jethro Gibbs prepares for his first Christmas without his wife and daughter, flashbacks reveal the unlikely journey that led to his first day on the job as a special agent at NIS’ Camp Pendleton office working with Mike Franks and Lala.