It looks like there's a rat undermining S.H.I.E.L.D., and their actions have painted the the super spy agency as some kind of criminal enterprise in the promo for the latest episode of "Marvel's Agents of S.H.I.E.L.D. LMD."

The big question, obviously, is who the traitor could be. One key suspect has to be Holden (John Hannah) -- we already know he's up to something with May (Ming-Na Wen), and the promo shows him instructing Aida (Mallory Jansen) to activate something menacing called the "Sunset Protocol," but is he really the prime mover here?

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More importantly for Aida and Holden, it seems that May is getting closer to discovering the truth about what has happened to her. She might take a punch that lands her on the floor in the promo, but you certainly wouldn't expect a little thing like that to keep her down for long, and the payback will probably hurt plenty.

Airing Tuesdays at 10 pm ET/PT on ABC, “Marvel’s Agents of S.H.I.E.L.D.” stars Clark Gregg as Agent Phil Coulson, Chloe Bennet as Daisy “Quake” Johnson, Ming-Na Wen as Melinda May, Iain De Caestecker as Leo Fitz, Elizabeth Henstridge as Jemma Simmons and Henry Simmons as Alphonso “Mack” Mackenzie.