Breaking Bad

It's the moment Breaking Bad's unrelentingly tense fourth season has been building to ever since Gus wielded that bloody box cutter in the premiere.

Breaking Bad postmortem: Giancarlo Esposito reacts to the premiere's most gruesome scene

After being unable to blow Gus ( Giancarlo Esposito

) to bits in the season's penultimate episode, Walt ( Bryan Cranston ) and Jesse ( Aaron Paul ) now find themselves scrambling for a Plan B. And the stakes couldn't be higher."[Episode 12] is just a little taste of what is about to happen," Paul tells TVGuide.com. "Everybody is kind of scared for their lives."Indeed, but Paul's character may be in the trickiest spot of all. Jesse spent much of the season being groomed by Gus to replace Walt as the chief meth-cooker. That ultimately led to a bloody fistfight and falling out between the two partners until Walt convinced Jesse that Gus had poisoned the child of Jesse's quasi-girlfriend.

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But despite the rift between them as late, Paul says Jesse remains loyal to Walt. "I don't think it's hard for Jesse to turn his back on Gus whatsoever. I don't think he was ever really an ally to Gus," he says. "I definitely don't think he trusts Gus. It's very easy for him to make this decision to go after Gus because he knows that he is behind [the poisoning] and that he is just an evil, evil, evil human being."With Walt, Jesse's always wanted to trust him because really, that's all he has left," Paul continues. "I think at this moment in time, he's going to team up with someone that he cares about. He's got his partner back and I think he's happy about it."At the same time, Jesse figures prominently in Gus' plans to find — and kill — Walt. "[Gus has to] make his move before he gets moved on," Esposito says. "He knows that if he can get Jesse out of that hospital and back to cooking, he then can grill Jesse. So he's trying to get Jesse back to the lab so he can really put Jesse on the hot seat and find Walt."

AMC orders 16-episode final season of Breaking Bad

Esposito also says that, although Jesse has threatened to no longer work for Gus if any Walt is killed, Gus no longer has any choice. "He'll have to kill Walt — period," Esposito says. "The game is over. He's just got to take Walt out. He can't negotiate with Walt. It's done. And he thinks Jesse will cook even though he says he won't do it. ... I don't think Gus is as worried as he probably should be. He believes he is still a few steps ahead."Paul, however, doesn't think Jesse will just roll over any more. "This season, you finally saw Jesse stand up on his own and take charge, take control," Paul says. "It was nice to finally not be beaten down, but be the one shooting the gun. Jesse is coming into his own and I think he's going to take that stand and show who he truly is. He's not going to be used as a pawn anymore."Pawn may just be the best word to use, given creator Vince Gilligan 's repeated use of chess analogies to describe the battle between Gus and Walt this season. But who will be checkmated in the (final?) showdown between these two men?

Check out photos of the Breaking Bad cast

"It's the culmination of a lot of chess playing, a lot of gamesmanship," Gilligan says of the episode, appropriately titled "Face Off." "This really is Spassky versus Fischer, and we're not going to know until the very end which one is Spassky and which one is Fischer. Hopefully, it will be a hell of a chess game. I'm hoping the main thing people say when it's all over is, 'Wow!'"Paul doesn't think Gilligan has anything to worry about in that regard. "You truly haven't seen anything yet," he says. "People are going to be screaming and yelling at the television set multiple times and definitely [be] on the edge of their seats. They're going to struggle to hold on. It's definitely a crazy ride."Breaking Bad's Season 4 finale airs Sunday at 10/9c on AMC.