When Lala's favorite CI is shot, the team joins forces with Oceanside PD to determine who was behind the attack; Franks visits his brother Mason at the compound; Gibbs' relationship with Diane is tested when she gets a job in Los Angeles.

The team investigates the murder of a Marine who had recently been picked for a classified mission; Wheeler's personal life is upended; Lala is thrown by unexpected news from Vera.

When an anonymous tip leads to the discovery of a young Marine's body at a chilling crime scene, Randy believes it could be connected to a previous case where a coin was left in the victim's throat.

When a naval officer mysteriously dies in the ‘90s, Gibbs and the team travel to the small dust-blown town of Serenity, Calif., where they encounter secret-harboring residents, an uncooperative sheriff and an investigation that will reverberate for decades.

Tensions rise when Franks' estranged older brother, Mason, blows into town, desperate for help after hitting rock bottom; the team investigates the robbery of a Navy bank; Lala, still struggling after her accident, makes a decision about her future.

When Dr. Donald "Ducky" Mallard, a liaison from D.C. headquarters and an old acquaintance of Gibbs', arrives to evaluate whether Pendleton needs an in-house medical examiner, not everyone trusts that's the real reason behind his visit.

When the body of a college swimmer washes up on the beach, the team must determine if it was an accident or murder; Gibbs prepares for his first interrogation.

Gibbs and Franks investigate the disappearance of a young Marine connected to a mysterious compound with a charismatic leader; Lala's fate is revealed.