LONDON — Extraordinarily for an opening-night film — and extremely heartening for aspiring filmmakers everywhere — Kai Barry’s first feature “Newcomer” came to the Raindance Film Festival programmers’ attention though open submissions. But after his film’s debut at the festival, Barry won’t be under the radar for much longer.

Filmed in Belgrade and starring “My Brother the Devil’s” James Floyd, “Newcomer” tells the story of Alex, an apparently bright young man who finds himself over his head when he applies for a job with a private firm protecting secret information.

Barry says: “The original thing was, I read a stat that said, in the U.S., 70% of the intelligent budget goes on independent contractors. Just reading that statistic, I thought, ‘There’s got to be a lot of confusion here, right?’ And I started to wonder: what is that world? Obviously there’s the James Bond world, but what about this world, where nobody knows who anybody really is? Misinformation can be as powerful as shooting people, or blowing things up, and that was the side of the spy world that I wanted to play with, and I wanted to keep everything as real as possible from that point forward.”

The result is an ingenious genre film that shows its hand when Alex’s first mission goes disastrously wrong and his entire team is wiped out in a matter of minutes. Accused of being a traitor, Alex goes on the run, and with only a sound recording of the murders to go on, he must piece together the events of the night, constantly imagining different scenarios.

“The most fun thing about spy movies — or any movie, really,” says Barry, “is when you suddenly look at everything differently. That was the goal. Each time you get a new piece of information, you start thinking, ‘Oh, this must be what the story is.’ And then it changes.”

This, says Barry, required a lot of planning. “You can’t really make a film like this without planning. I’d love to say I could just wing it, but that’s just not possible. I think I have a fairly spatial mind, but this film was very confusing to figure out, because you keep coming back to that same location and looking at it in different ways. So I drew out the whole set beforehand and made a 3D model of it, and at first we were going to build a stage and shoot everything that way. But we didn’t have the money to do that, so we had to find a location. We managed to find a location that was pretty similar but it still changed everything. Every little detail suddenly mattered — where the doorways were, how they moved in and out — so I had to then basically fine-tune the whole thing.”

What’s most impressive about “Newcomer,” however, is its commitment to realism: each new scenario is as plausible as the next. Do they all stand up to scrutiny?

“I’m sure if somebody looked really, really hard, they don’t,” he laughs. “But I definitely tried to think through every single bit of it, and James and I worked a lot on that together. There was a lot of ‘Does this make sense…?’ It’s easy to show something happening and then later say, ‘Actually, we lied to you.’ It needed to be plausible. We didn’t want to betray the audience.”