That was a great choice for the 400th episode of NCIS.

The background of Gibbs and Ducky's long-standing friendship was explored on NCIS Season 18 Episode 2.

The murder case that brought them together in 1980 was neatly tied into a modern-day death.

Even better, the 40-year-old case was that old TV trope, "the one that got away," for Gibbs and Ducky.

Gibbs has always been "boss" to his younger agents, from Tony, Kate, and McGee in the beginning and to Torres and Bishop now.

But the friendship between Gibbs and Ducky has been a prominent part of the NCIS tapestry from the start.

Ducky has always been the one who has tempered Gibbs' impulses. And Gibbs is the one who punctures Ducky's scholarliness.

The flashbacks from 1980 proved that it's always been that way.

Young Marine Gibbs had made a hasty life choice, while young Ducky was running away from a sidetracked medical career.

The treat here was watching how Fate threw these two opposites together, with the already eccentric Ducky hitting the car of the thug that had abducted GIbbs.

It was like they were meant to be together.

The pair was also being dragged toward their future callings.

Gibbs, about to head off to sniper school, was more than content to drown his sorrows over breaking up with his soulmate, Shannon.

Ducky was relentless while attempting to get Gibbs back on his right path. Some things never change. Even more so than a series of directors, Ducky has always been the one to call Gibbs on his shit.

If budding crime boss Jonny Zucado, hadn't insisted on interrupting their pub crawl, who knows where Gibbs and Ducky would have ended up?

But without Ducky serving as catalyst, there would have been no case of the week on this 400th episode. He caused Freckles to panic in the past, stashing the key card under the dry wall when Ducky pointed him out to Agent Scott.

Also, Gibbs wouldn't have become Gibbs, whose stoic exterior covers up a world of hurt. GIbbs, who NCIS helped to heal.

Gibbs returned the favor to Ducky, pointing him toward becoming a medical examiner as a way to satisfy his intellectual medical curiosity, while helping victims to gain closure.

Each also became a sounding board for the other, as well.

It was also Ducky who convinced Gibbs not to hunt down Jonny Zucado but to find himself a more well-rounded life.

But the fact than Zucado got away with murdering his cousin rubbed them both the wrong way for decades.

Not surprisingly, Sean Harmon has been an inspired choice to play a younger version of his father.

But the real find has continued to be Adam Campbell, who is a dead ringer for Man From UNCLE-era David McCallum.

Flashbacks should always be utitlized in small doses. But this trip back in time to the start of Gibbs and Ducky's friendship was particularly effective.

Also well done was the connection between past and present, as the Zucados again raised their ugly heads in Gibbs and Ducky's world, instead of staying under their rocks.

Also, phrases from the past rose up again in the present, binding the two together.

It was amazing that Vance didn't seem to know about the connection between Gibbs and Ducky and the Zucados.

The reminder of the Zucados walking free grated particularly on Gibbs, as he viewed them in total as one that got away, and there haven't been a lot of those during his NCIS career.

Even Ducky suggested Gibbs go see Jack, with Jonny Zucado resurfacing around the same time as Gibbs' anniversary with Shannon.

Frankly, it was surprising that Jack didn't intercede, as she's tried to do multiple times with GIbbs.

But then, this was Ducky's episode, not hers. Hers will be sadly coming with Maria Bello's upcoming departure.

His team was also certainly aware of Gibbs' added burst of intensity. But they knew enough to stand back out of the way.

Frankly, as with any spotlight episode, the rest of the cast was just there to make brief appearances to move along the investigation.

It was wonderful to watch Freckles, played by the always reliable Louis Mustillo (Mike & Molly), roll over on Jonny with minimal effort from Torres.

It was also appropriate that Ducky was the one to put away Jonny, finding his DNA with methods that weren't available in 1980.

Unfortunately, the downside is that now we'll get only the occasional visit from Ducky. Palmer tries, but he just doesn't give off the same degree of eccentricity.

Adding little was McGee's decision to celebrate his decision to become an NCIS agent 20 years ago. This was significant why, exactly?

Everyone trying to cajole Gibbs into coming was jarring in the midst of Gibbs' oldest enemy reappearing.

Besides, was anyone surprised that Gibbs decided to attend at the last moment?

That was just a way to reinforce that a weight had been lifted from Gibbs' shoulders after he captured his white balena.

Does it depress anyone else that the nervous probie of yore has become a boring, settled-down dad? He used to be the unit flake.

To recall your favorite Ducky moments, watch NCIS online.

How did you like the Gibbs-and-Ducky origin story?

How did this stack up as a special episode?

Did you like Young Gibbs or Young Ducky better?

Comment below.

Dale McGarrigle is a staff writer for TV Fanatic. Follow him on X.