For three seasons, CBS's Person of Interest has tried to raise questions about who's watching us. But starting Tuesday, the show will shine a light on a subject producers think no one is keeping an eye on quite enough: artificial intelligence.

"Since the show initially premiered [in 2011], we used to get a lot of questions about [surveillance] and whether it was a real thing or not, and I think what initially seemed like a science fiction concept became factual and something people know is pervasive," said executive producer Greg Plageman, referring largely to the 2013 Edward Snowden leaks.

"Now that everyone understands that, we said, 'What's the next thing coming along that's interesting, the next big thing happening and a little bit under the table now but clearly imminent?' And that is artificial intelligence."

The subject has always been of interest to creator Jonathan Nolan, but in plotting Season 4, which debuts Tuesday night, it was hard to ignore the flurry of activity in the AI community, particularly Google's January acquisition of Deep Mind, the company's addition of leading AI researcher Ray Kurzweil, and Facebook's interest in the realm.

Forced to take on new identities created by Root, the team, including Harold Finch (Michael Emerson) tries to adapt to their new lives in the season premiere of 'Person of Interest.' Image: Giovanni Rufino/Warner Bros. Entertainment Inc.

"So much of it is happening right now at such a rapid pace but its away from any public scrutiny, and we think that's extremely interesting," says Plageman.

In his view, he adds, the last comparable example of potentially world-changing research was the Manhattan Project. "The interesting thing about artificial intelligence is that it can be just as groundbreaking and just as big of a danger," he says.

How, exactly? Plageman points to ideas he first read in James Barrat's Our Final Invention, a book that laid out how, if not approached carefully, AI could be the end of the human era. "The point he brings up is, essentially, what [an artificially intelligent entity's] drives are programmed to do is essentially what it's going to do. It's not out to get us, but maybe we could become collateral damage in what its ultimate goal is," he says.

"So we create an artificial general intelligence initially, but the question is how quickly we move from an AGI to a ASI [artificial superintelligence]."

On POI, we will learn this season, these are all questions Harold Finch (Michael Emmerson) had when building The Machine, the mass surveillance computer system that has driven the show's plotline since its start.

"I think that's sort of a fun exploration point for us narratively that we'd like to explore — the origins of how Finch built his machine versus what's happening with the machine that [Finch's former classmate and friend] Claypool initially developed," he says. "We think it's important that people understand the different between the two machines, and I think the way we can narratively best illustrate that is to show how Harold built his machine and the various iterations that he went through."

Much like J. Robert Oppenheimer's chronicled doubts during the development of the atomic bomb, viewers will see Finch struggle with moral questions of his own via flashbacks, says Plageman. "The resolute faith that Root has always had in Harold's machine, he doesn't necessarily share with her, and we're going to find out more this year about why. And we're going to see with Samaritan, what happens if someone hadn't taken the same care in understanding and building the machine.

"What we're talking about this season is a cold war between two machines."