Malachi Kirby—an English actor who appeared in BBC staples EastEnders and Doctor Who before landing the role of Kunta Kinte in the Roots remake—is exactly the kind of talented up-and-comer that seems perfectly suited to Black Mirror, Charlie Brooker's techno-horror anthology series. But when Kirby was asked to audition for the starring role in "Men Against Fire"—which is arguably the darkest installment of the third season, now on Netflix—he hesitated, though not for the reasons you might expect.

"I was slightly… reserved about taking the job," Kirby tells me with a laugh. "Because I would find out what happens in the show!"

Kirby isn’t alone in his desire to insulate himself from Black Mirror spoilers. Since its 2011 debut, Black Mirror has earned a devoted following for its nightmarish, twist-laden stories about a series of possible futures in which the consequences of technology are extrapolated to their logical extremes.

"Men Against Fire" is well within the traditional Black Mirror wheelhouse. Kirby stars as Stripe, a soldier whose unit is tasked with finding and exterminating "Roaches"—fearsome, sub-human creatures who spread violence and disease across England. What’s it like to be immersed in the Black Mirror universe? Kirby takes us inside "Men Against Fire".

__Black Mirror is notoriously secretive—enough so that I had to sign a non-disclosure just to watch your episode. So when it comes to actually starring in one of these episodes, where do does the process even begin?__

I had to audition for it, sometime around February or March of this year. I met with the director, Jakob Verbruggen, and it didn't feel like I was having an audition. It was like he changed the audition room into the location of the scene. I was holding up a jacket that was supposed to be someone that was dying, and he was running around the room with this camera. But it was so amazing. And we had a discussion after, about the vision that he had, and I jumped onboard.

Did you and your costars do any kind of weapons training or boot camp? It can't be easy to just hop into the boots of an elite military squad.

I had done about two weeks of previous training for a film I did called Kajaki [later released in North America as Kilo Two Bravo]—but it wasn't so much focused on weapons. On Black Mirror, we were more focused on technical stuff. Learning how to use guns, and doing close combat rehearsals for the fight scenes. It was really interesting learning how to use a gun. I had never really had much time with an actual gun… and I was kind of surprised they gave me one to use. They're telling me, "Don't fire on someone. Because it will kill them." And I'm going, "Okay!" [laughs] But we had at least three or four days of just combat rehearsal.

Shooting something as grim and violent as "Men Against Fire" can't be a cakewalk. What the atmosphere was like on set?

Freezing. [laughs] That is definitely one thing I remember. It was really, really cold. But the other actors were amazing, and we had this camaraderie very quickly. I think the cold helped. It isn't the most comfortable circumstances. You're in the freezing cold, in the middle of nowhere, shooting until whatever hour in the morning. But everyone was very excited about Black Mirror—so every day, everyone was excited to be there. Which is nice. And not always the case.