As “Trespassers” wears on, you start to think the couple that gets killed mere minutes into it had it easy. While the masked men that unload a magazine’s worth of bullets into the pair on the side of the road seem merciless, they don’t seem to hold a candle to what pain can be inflicted by the two couples that have rented the newly deceased’s pair’s desert home for what’s intended to be a weekend of fun in Orson Oblowitz’s taut and vicious thriller.

“It’s like the owners were in the middle of developing something,” Sarah (Angela Trimbur) remarks upon a tour of the house, which includes a dark room for photography, and the same could be said for herself in how she relates to the others joining her in the Mojave, trying to get back in a groove with her boyfriend Joey (Zach Avery) after an emotionally trying year and with her estranged best friend Estelle (Janel Parrish), who brings by her obnoxious new boyfriend Victor (Jonathan Howard). Surely, the masked men who already slaughtered the owners of the home to find something inside will return to take out their AirBNB guests, but Oblowitz and writer Corey Deshon make things interesting well before that time comes by sowing seeds of distrust amongst the quartet who haven’t exactly been forthcoming with one another and begin looking out for their own self-interests during the retreat where they were supposed to come together.

Pity the poor woman (Fairuza Balk) who knocks on their door, claiming her car’s broken down, but by then as Sarah wonders whether it’s safe to let her in, it’s clear that danger has already entered and isn’t going away when not only everyone is so capable of wounding each other emotionally but their resentments have made the availability of kitchen knives particularly concerning. Like “Who’s Afraid of Virginia Woolf?” by way of Dario Argento, “Trespassers” keeps tension running high throughout when the obvious villains give way to far less obvious ones and anxiety manifests itself into questionable choices and the bold, sweaty colors that come to drench the proceedings. Featuring a standout turn from Trimbur and muscular direction from Oblowitz, the film is as relentless and unforgiving as any of its characters and on the eve of its release, the director spoke about following their lead in pushing the limits, embracing the old school chamber drama inside this ultramodern horror film and the discoveries made by shooting the story sequentially.

How did this come about?

I had been friends with Julio and Diego [Hallivis, the producers] for a couple years. We met each other on set when we both started out in L.A., working together and I had showed them my first movie “The Queen of Hollywood Boulevard,” which I was in the process of finishing and asked for their advice for distribution. I guess they dug the film because a couple weeks later, they called me and were like, “Dude, we’ve got this awesome script. We’d really like you to bring your style and voice to it.” So they brought me “Trespassers,” which at that time was called “In Camera” by Corey Deshon and I saw a really cool opportunity to not only work in the horror genre, which I love, but also to make this horror movie that was also a drama as well.

That was something I really liked about this – you could describe it as a relationship drama that goes to some really grisly places. Was it tricky to get that mix?

Yeah, that was to me was what made it interesting was that it was a relationship drama. Corey Deshon [actually] based this film on “No Exit” by Sartre and the heart of this film is that all of these characters are a reflection of each other’s good and their bad. That is the horror of the movie is that we see ourselves in other people’s views of us. And the genre side I wanted to bring, and Corey did as well, is that no matter who we are or what we think we are or how important we think our issues are, the world is much bigger and much greater and much more complex than anything we can understand. Sometimes it’s a thousand miles away and sometimes it finds itself on your doorstep. The world is a horrific place and sometimes those horrors find themselves knocking at the door.

When it’s a single location like this, what was it like to find the right house?

It took a couple months because, to me, the location was the central character of the film and it made or broke it, so Julio and our line producer Nicole [Flores] really just went out to tons of locations. We did a bunch of scouts and finally we found the right one and I don’t know how they made it work within our budget, but they did and it was awesome. And there was basically three iterations of the script. The first one took place in a tropical location. Then we decided to change it to the desert and then into a modern home, a luxury home. Once we found the home, we really manicured it so the action and everything would take place using the amenities of the actual location that we had.

Is it difficult to make that dynamic when you’re confined to single physical space?

That’s the first uphill battle and I think you fight that battle all the way until the film is out in the world because in preproduction, we’re trying to write it so that there’s enough tension and drama between the characters so that even that is interesting enough to keep you enthralled. Then in the staging of the film with my production designer Michael Conte, we rebuild a lot of the interior of the house, so there would be locations within one location, so you’re never actually just in one room. You’re actually in a bunch of different rooms within one place and then with the visual language with Noah Rosenthal, my [cinematographer], we tried to keep it interesting and keep it moving. Obviously, the actors really brought a lot of intensity [as well] and we created a kind of improvisational environment, so that it wouldn’t feel stilted. It would always feel a little more energetic and kinetic and then in the editing, Brett Solem, my editor, really brought this pacing and tension to the film and Jonathan Snipes, my composer, did [too] with the score and my sound designer Ugo [Derouard] really pushed that. So every step of the way, you’re really fighting this battle of how do we keep this interesting, never leaving this house.

I understand it was shot chronologically – were things happening on the set that might not have been expecting, but you could build into the story?

Absolutely. We weren’t changing much of the plot, but we were changing character arcs. A lot of it was really allowing the characters to be pushed into whole new emotional levels than we originally planned and upping the drama and really seeing what relationships during shooting were happening and ramping up the tension between them, especially when you see the Estelle and Victor relationship. That relationship on paper was not really what [what it is now] and if we hadn’t shot chronologically, I don’t think we would’ve seen it go to the intense levels that it goes to. And as a director you can get a little lost when you have all these elements that you’re trying to hold onto [when scenes are shot nonsequentially], so doing it chronologically, it was much easier to keep track of where everyone was and then push where they could all go.

Is it true Fairuza Balk’s character “The Visitor” was actually written as a male before she came in?

Yes, it was a male character originally, and as all of us — Julio and Diego, the producers, Corey and I would sit around talking about it, we decided who the hell is going to let a man into their house [in this situation]? I think we’re moving past these kinds of stereotypes, but there was a science experiment that was done of people driving by a person with a broke down car and nine times out of 10, they never stopped for the man, but it was something like two out of three times, they stopped for the woman. That’s just the nature of society, the nature of culture, so we were like, “Let’s subvert the idea and let’s make it a really neighborly, nice, disarming woman,” and it [made sense] for Angela [Trimbur]’s character arc that she would let that character in.

Then we were super lucky to get Faruiza. That’s not the character that was written, and she really came in and was like “I want to dress like this, I want to be like this character and I want to do it this way.” At first, I was like I don’t know. I’m a much more stylized person. I like big characters. But she was right [to be more subtle]. That character she brought is really awesome and really special and from the second I put her on camera, I knew, “Oh, I just need to do whatever she wants…I need to step back.” And I remember she’d ask me, “Do you have any notes?” And I was like, “Notes? This is your character. You’ve got it. Let me just document it.” And that was a real big question mark that she really answered.

In general, it seems like you had to get really versatile actors since you see a lot of different sides to these characters’ personalities. Was that tricky to find?

It was very difficult. They’re very unorthodox characters because none of the characters are good and none of them are necessarily bad until…you know, a point in the film. [laughs] But that’s an idea we were playing with is that these characters aren’t good and they aren’t bad – they’re flawed human characters all dealing with real stuff. Jessica Sherman, our casting director, really brought some amazing talent in and we went to hundreds of auditions. I’m super grateful for these really diverse actors that came in and all brought a really different take on each character. And like I said, there’s a lot of improvisation in this film and I don’t think it comes off like that. I don’t think you’d know a lot of this film is improvised by these actors because they really knew the song they were singing.

Was there a particularly crazy day of shooting on this?

Yeah, the film was about 18 days of night shoots, so there was a point where we really hit pure psychosis and obviously there were some stunt days. The day in the pool was very difficult. It was extremely cold that night and Zach [Avery] was really giving us his all and he was in that pool for hours. That was a very intense day of shooting and we were fighting the sunlight and no one had slept. Then the day in the nursery room with Janel [Parrish] and Angela, it was about 100 degrees in there and we did not leave the room for about 12 hours. It was extremely emotionally and physically intense on both of them and I think everyone basically lost it, but you know what? I don’t want to speak for my whole crew, but they were such an amazing crew and such an amazing cast, I think we could’ve kept going forever. We were all so in love with it and so in love with the process that we were all just in it.

I think that comes through. What’s it been like bringing this out into the world?

We world premiered at Frightfest, [which] was awesome. We played to a packed house of about 700 people in one theater, which was an IMAX screen, and then in the other theater, it was a packed house with another three or four hundred [people] and the reaction was amazing. That moment where watching 700 people all gasping and jumping out of their seats was the single greatest moment of being a filmmaker. You live to make people physically react like that and it was amazing.

“Trespassers” opens on July 12 in Los Angeles at the Arena Cinelounge and in New York at the IFC Center and is available on VOD.