NCIS: Los Angeles is inching closer to filming for the season 6 finale.

The untitled episode will cap off a three-episode arc for the agents of the Office of Special Projects, closing out the season with an "enlightening" conclusion. Penned by Kyle Harimoto, the finale will be directed by executive producer John Peter Kousakis.

"The clock is ticking," Kousakis teased in March. "Working hard to make our fans happy and enlightened. #staytuned #jpkteaser."

As filming began for episode 23 on Wednesday, Kousakis hinted at some exciting writing coming for the finale.

"Kudos to my brother [Kyle] Harimoto," Kousakis wrote. "You will soon discover why. #staytuned #ncislaS6finale #TeamHariKousman."

As viewers wait for the May 18 episode, NCIS: LA will air "Rage," "Beacon," "Field of Fire," and episode 23.

Set to air on April 13, "Rage" will dig into Callen's past while placing the agent undercover once more. Callen will attempt to infiltrate a white supremacy group to track down missing nuclear material and Kensi will enter the fray as the G's tattooed, biker girlfriend. Meanwhile, Callen's first meeting with Hetty will be revealed.

Find out more when NCIS: LA airs Mondays at 10 p.m. ET on CBS. Click the video below to see a preview for "Rage."

Tags: NCIS: LA NCIS: Los Angeles television CBS