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The black ops mission to capture or kill Osama bin Laden was as top secret as they come and, as it turns out, so was the feature film adaptation of the true-life story. 

In fact, Zero Dark Thirty's cast, headlined by Jessica Chastain, Jason Clarke and Kyle Chandler were forbidden to speak a word of the hush-hush project to the press which caused a few problems for one cast member in particular.

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"As soon as I was cast I wanted to just scream it from the rooftops," revealed Chastain of the moment she found out she'd nabbed the part of Maya, a CIA analyst who anchors the film's hunt for bin Laden.

Speaking with ET at the Los Angeles Premiere, the much-buzzed-about star says, along with wanting to share her accomplishment, she longed to correct the misinformation being circulated about the flick.

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"I had to keep it a secret for a whole year and press was coming out saying that they were speculating that I was playing the wife of a SEAL, which just sort of made me more mad," she explained. "But I had to keep my tongue."

Zero Dark Thirty, helmed by Oscar-winning director Kathryn Bigelow, is out in limited release December 19.