Linda Hunt

NCIS: Los Angeles couldn't carry on without Operations Manager Hetty Lange (Linda Hunt), could it? That's just the question creator and executive producer Shane Brennan is prepared to ask in the sophomore CBS drama's final two episodes.

Tuesday's episode (9/8c, CBS) finds the team investigating the death of a Navy SEAL imposter who was set on fire. The investigation uncovers new intel on the whereabouts of a stolen canister of radioactive material that could be used to make a bomb.  

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But the real bombshell comes from a woman by the name of Lauren Hunter (Camelot's Claire Forlani), who shows up at the Operations Center and utters the phrase, "I am Hetty's replacement," just as Hetty mysteriously resigns.  Brennan acknowledges that the development is somewhat out of the blue, but he says that was by design.

"The chaos that causes within the team ... and the sense of 'Why weren't we told what the hell is happening here?' [is] what I think the audience will be feeling as well," Brennan says.  "We all get to experience it together in the last episode."

Indeed, Hetty's surprise exit in the penultimate episode doesn't mean she won't appear in the finale. "She is in the center of the episode," Brennan says. "She has no scenes with any of our regular characters, but Hetty is doing her thing. Is she in a position where she may not return? Absolutely.

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"You're going to see a side of Hetty that you haven't seen before," Brennan continues. "You're going to see something about her that's very revealing, and you're going to see Hetty fire an angry shot. She's going to discharge her firearm and she's doing so in anger. And she's not at the shooting range! It's self-preservation."

But Brennan maintains that the real journey of NCIS: Los Angeles belongs to Callen (Chris O'Donnell). As such, look for some major revelations in his ongoing investigation into his past. And as luck would have it, his secrets might just be connected to Hetty's.

"You're going to find out more about who he is, and you're going to be as shocked as he is," Brennan says. "He's finding out things in this last episode in particular that will totally rock him and totally rock the audience too.  It's the next step, but it's not a step — it's a leap. The questions everyone will be asking over the summer are: Who is Callen? Who is Callen really? And how much does Hetty actually know?"

NCIS: Los Angeles airs Tuesdays at 9/8c on CBS.