In the milestone 400th episode of NCIS, viewers are taken back four decades to the year 1980, revisiting the moment when U.S. Marine Sgt. Leroy Jethro Gibbs first encountered Donald “Ducky” Mallard. In a surprising twist, it’s Ducky, played by Adam Campbell, who inadvertently saves Gibbs’ life, marking a departure from their usual dynamic.
The younger version of Gibbs is portrayed by Mark Harmon’s real-life son, Sean Harmon. This unique episode brings both actors, Sean Harmon and Adam Campbell, together for the first time in their respective roles.
The narrative unfolds with Gibbs being kidnapped by Ringo Zucado, a member of the Jonny Zucado crime family, and trapped in the trunk of a car. Ducky, still adjusting to driving on the “wrong” side of the road as a newcomer to the U.S., accidentally collides with Ringo’s car. The minor collision results in Ringo’s death, though it’s revealed he was already stabbed. Despite the unintended fatality, the situation poses a threat to both Ducky and Gibbs.
NIS agents, the precursor to NCIS, discover Gibbs in the trunk and take him to headquarters, providing an opportunity for Gibbs to express gratitude to Ducky for the unintentional rescue. The two decide to grab a drink, but their plans take a dark turn when they are separately kidnapped by thugs from the Zucado family.
Under interrogation, Gibbs and Ducky endure beatings as Jonny Zucado seeks information about what Ringo might have revealed before his demise. Ducky discloses that Ringo was already dead when NIS arrived, sparing them from further harm. Gibbs, using his Marine background, convinces Jonny not to kill them by invoking the potential repercussions from the Marines.
Once free and bound by secrecy, Ducky implores Gibbs not to let fear prevent him from pursuing love. Gibbs, who has recently broken up with Shannon, heeds Ducky’s advice. Inspired by Ducky’s own loss of love, Gibbs reconciles with Shannon, and their journey together, including marriage and the birth of their daughter Kelly, begins.
As the younger versions of Ducky and Gibbs attempt to solve the crime, Ducky’s path leads him back to the medical examiner’s office. Having left the medical profession after a morally challenging experience at a refugee camp, Ducky rediscovers his purpose – bringing closure to victims’ families through forensic work.
Fast-forwarding to almost the present day, December 2019, Gibbs and Ducky find themselves drawn into another crime involving Jonny Zucado. Determined to achieve closure, they successfully exhume Ringo’s body, leading to the discovery of viable DNA under his fingers. This evidence results in Jonny’s arrest for Ringo’s murder, bringing justice to a crime that had remained unresolved for decades.