Screenwriter Alan Trezza discovered the concept for his new horror film Rosario during the pandemic. The project went from concept to completed script in just four weeks in a creative sprint fueled by 5 a.m. wake-ups and late-night writing sessions.

It all started when he wondered what it would be like to have to spend a night with a loved one’s body. This idea evolved further when Trezza, the son of an immigrant, began examining cultural assimilation in America.

These themes coalesced for Rosario, a claustrophobic horror film starring Emeraude Toubia as a Wall Street stockbroker who returns to her deceased grandmother’s apartment during a snowstorm. While waiting for EMTs to collect the body, she uncovers a hidden chamber filled with occult artifacts tied to dark rituals. It becomes a race against the sunrise for her to break an ancestral curse.

We spoke with Trezza about how he finished the screenplay so quickly, keeping the second act interesting, the importance of plant-and-payoff for horror, and more. Explore his process with us.

Editor’s note: The following conversation has been edited for length and clarity.

Final Draft: I noticed that a starting point for you was the pandemic. I’d love to hear more about your process on developing an idea.

Alan Trezza: For me, the hardest part of writing is coming up with an idea that I fall head over heels in love with. That is the hardest part, because it is like finding a soulmate, or it’s like finding someone you’re going to marry. It’s not easy. 

So many times, we have these ideas and we flirt with them. … And sometimes we have an idea that we’re so passionate about, but it’s empty. And we might wake up in the morning and be like, “Oh my God, what was I thinking with that idea?” Or worse, six months down the line, you wasted six months writing a script, and you didn’t love the idea. 

That’s the hardest part for me. But when I did come up with the idea for Rosario, and I’m not saying this to brag at all, but it took me four weeks to write it. And that just goes to show you, once you have that idea that you cannot stay away from, the rest, for me at least, is quite easy.

Final Draft: What was your outlining process?

Alan Trezza: I’ve done every scenario known to writers. I’ve done the whiteboards, and I’ve done the index cards, and I’ve done the treatments. 

What works for me is I write it out almost like a story, almost like it’s a short story with descriptions and dialogue and everything. And once I have it in that form, then I’ll know what’s lacking, or what I might be pressing too hard on. 

After that, I adapt that to screenplay format, and that’s what I’ve been doing the last few years, and it’s worked for me really, really well. If you just have those bullet points, I find that you get lost in the weeds. But if you have actual paragraphs in order and it’s something that’s pleasing to look at and pleasing to read, it soothes you into the story more and gets you more into what it could possibly be. Instead of just “bullet point, bullet point, bullet point.” It doesn’t feel real at that point. 

That’s my process, but everybody’s different, and everyone has their own way to get there.

Final Draft: Are you following three-act structure when you do that?

Alan Trezza: Only instinctively, not purposefully. I think three-act structure’s instilled in us from a very early age. We’ve been hearing stories even when we were in the womb. So I think it’s very innate. 

The trick is to do it instinctively. You don’t want to stick so closely to a page count, sacrificing character, sacrificing plot. So again, it’s instinctive, and if the midpoint comes a little past the midpoint of your script, that’s okay. It’s all organic. Everyone has their own take on the recipe.

Final Draft: Is there a portion of the script that you tend to struggle with? A lot of people hate that middle.

Alan Trezza: Yeah, midpoints are difficult, for sure. You want to make sure that you have a great twist in the story to have the audience lean forward and not leave their seat. That’s hard, because twists can make or break your story. So those are always difficult. 

But I find if you have a sequence that’s compelling, that’s emotional, where your antagonist and your protagonist face off, there’s some sort of heightened action or a heightened story point. And then from there, all bets are off. Those for me are the ingredients for a good midpoint set piece and the ones that I try to satisfy whenever I find myself racking my brain, “Why isn’t this midpoint set piece working?” 

Oh, well, [it’s] because things are still the same. It has to be a moment so that things are never the same after this. And the audience is going to start thinking, okay, now what?

Final Draft: Another thing that’s unique about this script is that it takes place for the most part in one location. What were the challenges of writing that?

Alan Trezza: For me, it was a matter of exploring different rooms, hidden rooms, different environments, and making sure that it never really felt too stagnant. 

But I think we were blessed with an incredible filmmaking team led by Felipe Vargas, our amazing cinematographer, Carmen Cabana, production design [by Carlos Osorio]. Everything made it seem claustrophobic, but not boring, or not just repetitive. They did incredible things with the lighting. They did incredible things with backdrops. The camera work was extraordinary, so they really made this small space look like its own universe.

Final Draft: I love the neighbor character [played by David Dastmalchian], and I wonder how you approach writing someone that pops up like that and has to be really big really fast.

Alan Trezza: We so often get the wrong impression of people the first time we meet them, and I wanted to explore that. He does not seem trustworthy. He’s coughing, he’s sick. Again, something that was inspired by the pandemic, not getting too close to anyone who might have a cough.

I wanted him to be this person who, for all intents and purposes, is the creepy neighbor, but at the end of the day, he actually ends up being someone—I don’t want to spoil it, but someone actually quite trustworthy and actually quite courageous. 

So I wanted to do that. I wanted to explore how sometimes when we see people and meet people, we get the wrong first impression probably because of our own hangups and baggage that we bring to it, not so much theirs.

Final Draft: Do you have techniques for creating effective scares on the page?

Alan Trezza: The first place your mind goes to? It should never be what you write down on the page. It’s always got to be four, five, six, seven steps down ahead. There’s a certain weapon that’s used in this movie towards the end to save one of the characters. … It’s a matter of really forcing and pushing yourself to do something you haven’t seen before in any other movie. 

So it’s hard. It is definitely very difficult because there’s centuries and centuries worth of horror films and scares. It’s actually one of the more difficult things to come up with. 

I do find that if you just let your mind go to the most wild place, a lot of the time, that’s where you end up.

Final Draft: How do you approach exposition?

Alan Trezza: It is a challenge, as well. It’s a necessary evil. Otherwise, how are we going to impart information to the audience? 

The way to do it is you have to hide it, you have to smuggle it, and oftentimes talk around it. Use metaphors to get across what the characters are trying to say. Never have characters say things to each other they already know. Never say, “You’re my brother. I’ve known you for 22 years.” You can’t do that. So you have to talk around it. If you can, use a metaphor to symbolize or to mean what the characters are saying.

Final Draft: What advice do you have for an up-and-coming horror writer?

Alan Trezza: Treat it like a job. Like I said, I wrote Rosario in four weeks because I wanted to see it. I wanted to experience it. I wanted to live in that world, but that also meant waking up at 5 a.m., writing until 9, and then going about my day, and then starting writing again about 8 p.m. and writing until midnight. And that was seven days a week for four days straight. 

That meant not hanging out with friends, not being able to check out movies. I had to treat it like a job, and I wanted to see if I could do it. Writing, if you treat it like a job, you’ll get it done. You’ll get there. … If you want it to be a hobby, great. Have it be a hobby. And maybe some people read your script down the line or maybe you can share it with some friends, but if your ultimate goal is to write a movie that gets made well, then there it is. 

I’ll tell you another thing, once that movie really starts to get made and money starts to be spent, you’d better believe you’ll be on a deadline, and you’d better believe you’ll be putting in those hours anyway, so just get used to it. Train your brain to be creative on command. Even if you don’t feel like it, even if you don’t feel like writing. “Ah, no, I’m not going to write today. I don’t feel like it.” Well, what if the guy who does the dry cleaning doesn’t feel like going to work? What if a doctor doesn’t feel like going to work. There are repercussions. So you’ve got to show up.

Rosario is in theaters now.