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 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.