What Is The "Index" On 'Agents Of S.H.I.E.L.D.'? Cal's List Might Include Guest Star Drea de Matteo

One of the major complaints about ABC's Agents Of S.H.I.E.L.D. during its freshman season was that events moved too slowly; there were too many "filler" episodes while the show waited for the paradigm-shifting events of Captain America: The Winter Soldier to occur. Well, that complaint certainly can't be levied against the show anymore, as events are now hurtling along at a breakneck pace: Skye is an Inhuman. She's also Daisy Johnson, aka Quake. Her dad is Calvin Zabo and her mom was an Inhuman mentor. Trip is dead. Bobbi and Mac are up to no good. There's a dude with no eyes who can teleport. Oh, and Raina transformed into a porcupine (or something). Amongst all these developments was a veiled reference that is perhaps the most foreboding of everything we've seen on Agents of S.H.I.E.L.D. : Cal's "index."

If you were too busy ogling Raina's newly-sprouted quills, you may have missed the doctor's threat to make trouble for Director Coulson by reconnecting with his friends on the "index." So who's on this index? And how worried should we be about it? Very worried, most likely. We've heard the term "index" on S.H.I.E.L.D. before, as it is the organization's list of super-powered people and things.

Appropriately, the synopsis for next week's episode, "One Of Us," promises all sorts of super-powered mayhem: "Cal seeks revenge on Coulson by assembling a team of Super Villains to destroy S.H.I.E.L.D.," it teases. Since Cal used the word "index" specifically, could he be finding these villains with S.H.I.E.L.D.'s own information? It seems as though the show, which started as a tribute to the "normal folks" who protect our world from otherworldly threats, is finally embracing its super-powered nature.

Marvel recently announced that actress Drea de Matteo (The Sopranos, Desperate Housewives, Sons Of Anarchy) had joined the cast of S.H.I.E.L.D. as a character with the not-at-all-villainous name Karla Faye Gideon. Apparently Gideon is the first name from the Index that the Doctor looks up, as she will be introduced in next week's episode as "a Gifted woman with a grudge to bear against S.H.I.E.L.D. who joins forces with Skye’s father, Cal," according to executive producer Jeph Loeb.

And though de Matteo is certainly the most famous name among that episode's guest cast, she's not the only one playing a villain. A close examination of the press release reveals that actor Jeff Daniel Phillips, best known for playing a Geico caveman, will appear as "David A. Angar." David Angar is the full name of a Marvel villain best known as Angar the Screamer. On the page, he possessed a Sonic Scream so powerful it can alter the chemicals in a human's brain, inducing hallucinations and even amnesia. (Could he have anything to do with this week's episode, where Thor's Lady Sif "has lost her memory after fighting with a mysterious warrior, whose true mission will send shockwaves through S.H.I.E.L.D."?)

Between Karla Faye and Angar the Screamer, it sounds like the Agents are about to have their hands full. Whether Cal has the pick of S.H.I.E.L.D.'s powerful registry or these two names are only the start of his own index, the back-half of Season 2 should be an action-packed sprint to the finale.

Images: Justin Lubin/ABC; heroesofourselves/tumblr; Marvel Comics