'Agents of S.H.I.E.L.D.' season 4 episode 15 spoilers: Jed Whedon's directorial debut to mark the end of LMD arc

Agents Simmons (Elizabeth Henstridge) and Fitz (Iain De Caestecker) are left to fend for themselves in a headquarters that is now swarming with life model decoys (LMDs) in the final episode of the LMD arc of "Agents of S.H.I.E.L.D."

Coincidentally, the upcoming episode will also mark the directorial debut of co-showrunner Jed Whedon. In an interview with IGN, Whedon said that he has always wanted to try his hand at directing and felt that this particular episode, which he also wrote, presented the perfect opportunity to finally get behind the camera.

Whedon shared that the episode will feature an ambitious fight scene that took them two days to film. It will serve as both the climax and conclusion of the current LMD arc. Knowing that this will be his first time to write an episode that he would also direct, Whedon readily embraced the challenge.

"I figured just throw me in the deep end and see if I can swim, and I did write a little bit of a deep end in some of it. I think it worked out," he said, chuckling

The official synopsis for the episode titled "Self Control" states that suspicion will quickly escalate to paranoia as Simmons and Fitz, who are allegedly the only human agents left in the S.H.I.E.L.D. headquarters, try to figure out which of their other comrades have been replaced with a robot.

The trailer also shows the sleazy Dr. Radcliffe (John Hannah) showing concern for his former allies after Aida (Mallory Jansen) informs him of the four additional LMDs that have been deployed into the S.H.I.E.L.D. headquarters. Radcliffe worries that people could get killed, but Aida argues that as long as nobody resists, there will be no bloodshed.

The brief scene really does beg the question: Who is really in charge of the operations at this point, Radcliffe or Aida?

Simmons and Fitz will hold the fort for as long as they can, but when the LMDs begin gunning for them, how long can they possibly hold out before they are completely overwhelmed and replaced by their very own LMDs? Will they be on their own to the very end, or will an unexpected ally appear to lend them a hand?

"Agents of S.H.I.E.L.D." season 4 episode 15 airs on Tuesday, Feb. 21, at 10 p.m. EST on ABC.