Kiefer Sutherland, Tzi Ma Kiefer Sutherland, Tzi Ma

The clock is about to stop ticking on another season of 24.

On Monday's Live Another Day finale (9/8c, Fox), Jack (Kiefer Sutherland) must find and apprehend Cheng Zhi (Tzi Ma) in order to prove that the United States wasn't responsible for bombing a Chinese ship and, in turn, prevent China from declaring war against the U.S. Of course, Jack might be a little bit distracted by the fact that Cheng also has Audrey (Kim Raver) trapped under the watchful eye a sniper who could take her out at any moment.

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Given both Jack's and Audrey's histories with Cheng, he was a perfect choice to be the final villain of this limited series. But even so, the actor who plays him couldn't believe the response to Cheng's return. "Oh, my God. I couldn't believe it!" Ma tells "They wanted this to be the surprise of the season. There were these posts on the 24 Facebook page, and there was one chain that had, like, 900 responses. "'I can't believe he's back! I hate this guy!' It was unbelievable — the chatter. I didn't expect such a fervent reaction."

Less surprising to Ma, however, was the fact that Cheng would come back even deadlier than before. "[The producers] said, 'Basically, you went rogue.' At that point, that's all I really needed to hear," Ma says. "Now the stakes are completely raised. Not only has he gone rogue, but he feels like he's been wronged. That makes it even worse."

Indeed, Cheng's return initially had nothing to do with Jack Bauer. Instead, he had conspired with the now-dead Adrian Cross (Michael Wincott) to obtain the override device he needed to frame the U.S. for bombing a Chinese ship and force his native country into action. "He really wants China to be at the top of the world," Ma says. "And since his government isn't listening to him, he has to take matters into his own hands. He does have some support in China, so he needs to awaken that sleeping giant. So, he's like, "OK, I'm taking initiative and when I get this thing going, you guys are going to see it my way.' His rationale is totally sound in his mind."

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Although Jack's involvement on the case was an unexpected surprise for Cheng, it's not entirely an unwelcome one, according to Ma. "That was something he didn't anticipate because Jack disappeared from the face of the Earth for four years," he says. "It wasn't something he wanted to happen, but when it did, you're talking about two roosters going at it. Jack is kind of his mirror image on the other side. He really wants to get the competitiveness up as an individual. So, it's always high stakes with Jack."

The duo is on a collision course in the finale, and while villains facing Jack Bauer don't usually get the best end of the deal, Ma says Cheng will never run from a fight. "He feels he's serving a greater good," Ma says. "At this point, it's almost like a religious zealot who completely loses themselves. In some ways, he's kind of in a trance."

Even if it means fighting to the death? "That's always a possibility," Ma says. "When you go into the arena, you know the outcome may not be good, But you go into the arena either way because you're a gladiator."

24: Live Another Day wraps up Monday at 9/8c on Fox. Watch previous episodes here.