NCIS' Tony DiNozzo will find that a certain coworker will inhabit his thoughts more and more as his departure nears.

Last year, NCIS bit Farwell to Ziva David (Cote de Pablo). This year, that loss will help inform Tony's (Michael Weatherly) decision as he opts to put his Special Agent career behind him. While we don't know if de Pablo will make a special appearance for Weatherly's final episode, she will certainly be mentioned.

"Tony's relationship with Ziva absolutely will have an impact on his reason to depart," showrunner Gary Glasberg told E! Online. "There's no part of Tony DiNozzo that Ziva David isn't a part of. She's a huge aspect of who his character is so it would be unfair and wrong to write this episode, to produce this episode and not have her character be a part of it."

Ziva's potential return will come just as the series introduces two new characters. In "Return to Sender," Gibbs (Mark Harmon) and FBI Special Agent Fornell (Joe Spano) began looking into the arrival of a rogue British spy, and that storyline will bring FBI Special Agent Tess Monroe (Sarah Clarke) and MI6 Agent Clayton Reeves (Duane Henry) into the fold. The pair will make their debut in episode 23, "Dead Letter."

The case of the missing spook will provide a through line for season 12's last four episodes. In next week's "Homefront," Director Vance and Fornell will travel to London to continue the investigation before the story really ramps up in the last two episodes.

"The NCIS team, alongside the FBI and MI6, continue an international manhunt for an escaped British spy who has left one colleague fighting for their life in ICU," CBS said of "Dead Letter" (episode 23). In the finale, "Family First," the team will continue the hunt as their target looks to attack current and former agents.

Find out more when NCIS airs Tuesdays at 8 p.m. ET on CBS. Click the video below to see a promo for the series' next episode.

Tags: NCIS television CBS