'NCIS: LA' boss on the season finale and the explosion that could spell disaster for the team -- EXCLUSIVE PHOTO

Cliff Lipson/CBS

NCIS: LA executive producer Shane Brennan promises an explosive season finale. Need proof? See the exclusive photo below.

"I've been doing this for 30 years and that explosion — in the world of blowing things up — is a triple A+," he says. "And that explosion, that hasn't been enhanced with any computer graphics at all, and when you see it on air, we have not touched it…. The audience, because they've gotten so used to seeing it on movies and in television, they often make the assumption that you've added some computer graphics — none. We have done nothing to it."

In this two-hour season finale, Callen (Chris O' Donnell) and the NCIS: LA team go toe-to-toe with their adversary, the Chameleon. And while in pursuit of a clue that will lead them to their bad guy, part of the team find themselves in a fiery situation at a warehouse, after their plan "goes a little south." "Now, I'll let you in on a secret: Kensi and Deeks and Sam go to the warehouse. Who's in the photo?" Brennan teases.

Cliff Lipson/CBS

While we're pretty sure Sam (LL Cool J, not pictured) makes it out okay (key words: pretty sure), that doesn't mean everyone does. "Something happens in the first hour that catches them by surprise. They're blindsided," he says. "Then in the second half of this movie-length finale, they're in uncharted waters. They've never experienced this kind of thing before, and it takes Callen to a place that is quite disturbing. And it takes Hetty to a place that she's been to before, and we've alluded to before in earlier episodes. So by the end of the finale, the audience will be asking what we're going to do next season because everyone is sort of facing in a different direction."

It's such a nail-bitter that Brennan (who has previously also worked on NCIS) issued a warning. "It is as upsetting of a finale as I've ever done — in terms of the audience not liking me very much when I'm done, when they're finished watching," he says. "Either one of these could have been a season finale."

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