The Rookie star Harold Perrineau on that final twist and getting his 'Denzel moment'

Warning: This article contains spoilers for The Rookie season 2 finale, "The Hunt."

Detective Nick Armstrong is a worse cop than we could have ever imagined.

On Sunday's The Rookie season finale, the back half of a two-parter, we discovered just how deep Armstrong's double-crossing went. Not only had he been working for the Armenian mafia for years, but he was still actively trying to help Serj Derian (Themo Melikidze) flee Los Angeles. After a half-hearted attempt to extricate himself from his situation, Armstrong dug in his heels even further.

John Nolan (Nathan Fillion) was dismayed to discover that his friend and mentor Nick Armstrong (Harold Perrineau) was potentially a dirty cop, but he quickly enlisted the help of training officer Nyla Harper (Mekia Cox) to try and prove his theory. When their plot didn't pan out, Nolan even paid a visit to serial killer Rosalind Dyer (Annie Wersching) seeking assistance, and she told him where to find Armstrong's secret stash of weapons and evidence.

But it didn't take long for Armstrong to figure out what Nolan was up to, and he made sure to stay one step ahead of Nolan, moving and planting the evidence in Nolan's home. By the time Nolan took a sledgehammer to most of his walls, Serj had told the cops Nolan was the other traitor on the force. With the cops bearing down, we're left to wonder just how our favorite rookie might get out of this one.

To get the lowdown on Armstrong's double-cross, we called up the dirty cop himself, actor Harold Perrineau, to talk about everything from how far Armstrong might be willing to go to potential parallels with Training Day.

ENTERTAINMENT WEEKLY: Did you always know Nick was a dirty cop or when did you first learn that? How did it inform your performance?

We knew it was coming. But the mandate was to play it earnestly, play it like he's really there for everybody. He's there to do the job that he's meant to do. I came in to be the knight detective and that's what I was going to do. I was going to be on the side of all of the officers and the rookies and everybody. I played all the things there as real, really grieving for his wife so working late nights, really smart and confident and all those things. The thing was I just never knew what it was that was in the background. Whatever Armstrong was doing, I didn't have any idea about it and so none of that would come through during the performance.

When you signed on for The Rookie, how many episodes was it for and then how did your role evolve?

It was originally supposed to be five episodes and end sort of in the middle of the season, and then he kept going.

So you knew things were going to take a turn, but you didn't know exactly what the details of that were?

Exactly. We started off, and I was asking [showrunner Alexi Hawley] if it was like Denzel [Washington] in that movie with Ethan Hawke — Training Day. I was like, "Is he like Alonzo?" He's like, "No, he is not. He's not that dude." We were really clear right off it wasn't maniacal. I could've had my King Kong scene, it would've been great (laughs).

Nick tells John he got in with the mob because of his wife’s medical bills, though he was clearly already doing it when his wife died because of what Rosalind found. Is that the full story or might there still be more to it?

Nick Armstrong is too smart and too calculated, so he gives you what he needs to give you when he needs to give it to you. And so I think he gave him enough to say, "Look, John, this is a genuine friendship. I genuinely like you. I had stuff I had to do. I had bills, my wife, I was caught up, and I'm a little bit of an action junkie." All those things. I think he told him some of it. I don't think he told him everything with the Derians. I don't think he told him everything with capturing Rosalind. There was so much going on with Rosalind and Armstrong that I don't think you'll get to the bottom of it.

For a moment, it seemed like he might redeem himself and try to back out of things, but instead he framed Nolan. What do you think fed that decision? It seems incredibly cruel for someone he’s been mentoring.

I think Armstrong is a guy that at the end of the day will always try to save himself. There are people like that. They're great and smart and they're really helpful; they have a lot of knowledge. But at the end of the day, if it comes down to you or him, he's always going to choose him. He's always going to bet on himself. There was a moment that he really tried to get it back, tried to redeem [himself], but I think once he shot Erin it was almost impossible to get out of it in any way clean. Even as an audience member, I remember reading it and I was like, "He shot that pretty little girl! He is done! It's over." Killing that kid, there's no way they redeem it, so you got to push it. You try to live another day. That's really where Armstrong was just like, "John, I really like you. It's just too easy. I just set you up because you're the most earnest." In that cynical way, Armstrong is like, "Nobody is that earnest, so I'm going to frame you."

Has he always been playing John, or do you think there’s real affection there, especially when it comes to stuff like giving him advice on Grace?

I think this all happened because Serj Derian lost it. I think Armstrong would have kept going and kept doing all the things he was doing, but this one wild card bad guy made a bad move, and everybody called in their chips. I think Armstrong really liked John and that's why I liked playing it like that. I liked playing like he wasn't planning on ever getting caught. Nobody plans on getting caught. They just keep planning on how do I keep this going? He would have kept going had this event not happened.

How far is Armstrong willing to go to perpetuate this lie?

That is really tricky. If there's a season 3 and we get to explore that, that'll be interesting. Armstrong will always bet on himself. Armstrong will push it all the way to the end; that'll be the most dramatic. He'll push and push and push to try to frame John, probably until he has to die. That's a theory, but I think — even given the genuine friendship — he'll never say, "Alright you got me, I'll just go to prison." I don't think he'll want to do that. That's a terrible fate. You might as well shoot yourself. You don't want to put yourself in prison as a cop. That's not gonna be fun.

Is there any hope for redemption at this point?

I like Armstrong. I liked the character. There are a bunch of really great writers; if there's a way to redeem him, I think they'll find it. It'll be hard. Like threading a needle. I don't think it has to be the end because all that stuff I said about him betting on himself, that's me, Harold the actor, trying to figure out how to play it. If there is a way to save it, they'd be able to figure it out. Paying some kind of penance, having to be in prison, and being a mole. Or we find out it actually is a double double-cross. He could be really actually working for the FBI and he has to set up John because he's so deep undercover. We could find it for sure. But that's an Alexi call because it his show and it's where he wants to go. But I truly do dig Armstrong and I wish the best for him.

Between the LAPD and the mob, has Armstrong signed his death warrant? Is there any scenario going forward where he doesn’t end up dead?

If it weren't a TV show. If it were real life, he hasn't signed his death warrant. He's gonna keep playing cards and figure it out. In a TV show, John's our hero, so we can't let him go down. The show can't be bad detective; it's called The Rookie. We gotta save the hero. I enjoyed being there. I think they enjoyed me being there as well. If we could find a way to keep playing, I would love that. If not, it's great fun. But if I get a Denzel moment, you should know for sure he's going to die (laughs). I could still get my King Kong moment one day.

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