When screen legend David McCallum passed away in September, NCIS fans wondered how the show would deal with the sudden departure of his beloved character, Dr. Donald "Ducky" Mallard.

Now we have the beginnings of an answer to that sad question.

The show set the stage for Ducky's departure with the final scenes of NCIS Season 21 Episode 1.

And in the episode set to air on Monday, February 19, the NCIS crew will get the chance to say goodbye to one of their own.

Poignantly, the episode was co-written by Brian Dietzen, who plays Ducky's fellow medical examiner -- and former assistant -- Dr. Jimmy Palmer.

The previous episode concluded with Alden Parker (Gary Cole) receiving an urgent phone call.

We only heard his half of the conversation, but viewers were quick to assume that the call had to do with Ducky.

Titled “The Stories We Leave Behind,” this week's installment will show Ducky's colleagues learning of his passing and paying tribute as only they can -- by solving the case he was pursuing in his final days.

Ducky last appeared on camera in NCIS Season 20 Episode 22, popping in via video chat during his international lecture tour in order to help the team with an investigation.

Now, the co-workers who were so frequently awed by his brilliance will honor his memory by cracking the case.

"This episode is a retrospective look at the life and career of the charatcer Ducky Mallard," Dietzen explains in the preview above.

"We're paying tribute to one of our icons on the show," adds Wilmer Valderrama, who plays Nicholas Torres.

"The story itself, co-written by Brian, has to do with a case that Ducky was pursuing what up to the point where he passed away," says Cole.

“The case was important to Dr. Mallard. In [investigating it], they’re going to relive their memories of a coworker and a man who meant so very much to them,” co-showrunner David J. North told TV Line this week.

“Brian shed tears writing it; the cast and crew shed tears shooting it.”

Ducky was a member of the NCIS family from the beginning, and this episode is certain to be an emotional one.

Tributes to McCallum from Mark Harmon, Michael Weatherly and other former co-stars began pouring in immediately after his passing became public knowledge.

There were hopes that some past NCIS stars would return for the Ducky tribute episode, but it looks like Harmon and company will only be featured in clips from old seasons.

Perhaps that's the best approach, as it will keep the focus on McCallum's life and work -- and the character fans held so dear.

Hit the comments below to share your favorite moments featuring Dr. Donald "Ducky" Mallard.

Tyler Johnson is an Associate Editor for TV Fanatic and the other Mediavine O&O sites. In his spare time, he enjoys reading, cooking, and, of course, watching TV. You can Follow him on X and email him here at TV Fanatic.