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

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

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.

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

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.