The NCIS: Los Angeles cast and crew are creeping ever closer to the filming of their 100th episode.

Slated to be episode 504, the title for the milestone installment has yet to be announced. However, executive producer John P. Kousakis has been sprinkling hints about the plot while documenting the filming of episode 503, "Omni," on his Twitter feed.

"To all anticipating a small tease...Callen encounters a recurring nemesis in Ep.504-100! #NCISLA #morespoilstocome #staytuned #manythanks," Kouskais tweeted on Thursday.

With the extremely high number of enemies that Callen (Chris O'Donnell) has accumulated over the years, it is rather impossible to guess who the episode's baddie will be.

However, there is always the chance that the plot could tie into Callen's mysterious past, a tantalizing storyline that Kouskais has promised to elaborate more on during the upcoming season 5.

"GCallen spoiler...more family history revealed early in S5. More on all cast throughout S5. Stay tuned! Fun begins in 7wks! Tick Tock," Kouskais teased his fans in early August.

It appears that both Callen and Deeks' (Eric Christian Olsen) pasts will see major development throughout season 5, something that will make their avid fans happy.

Meanwhile, behind the scenes photos are flooding in for "Omni." Written by Kyle Harimoto and directed by Larry Teng, it appears much of the episode will be shot on location. This isn't too surprising considering the main theme of the episode is fast cars.

NCIS: LA returns to CBS on Sept. 24.