It is easy to understand how Hannah (Juno Temple) gets pulled into the orbit of Theo (Simon Pegg), a rakish and charming music producer, in “Lost Transmissions” since writer/director Katharine O’Brien lures you in the same way. Entering a cozy living room where Theo is holding court at the piano, playing whatever comes to mind, at the start of her feature directorial debut, O’Brien lurks around with the same knowing mischief as he shows tooling around trying to find the right key, her camera levitating as if all the warm, vibrant energy inside is holding it up, ultimately locating Hannah, who becomes the unwitting subject of a song.

It’s a bewitching moment in which she’s smitten, but the spell is broken not long after for the aspiring songwriter, if not the audience, when it becomes clear that Theo has trouble staying on the medication that keeps him in line, having once severely injured himself during a bad acid trip during the ‘90s at the height of his success that rearranged his neurons and led him to be diagnosed as a schizophrenic. Yet Hannah stays to take care of him upon seeing no one else will, and for the duo who keep their ears attuned for those moments when the perfect arrangement of sounds cohere into beautiful music, their time together may not promise to be harmonious by any traditional definition, but beautifully complimentary on its own terms.

O’Brien hits all the right notes in “Lost Transmissions,” which settles into the Los Angeles music scene like slipping on a pair of loose-fit Levi’s as it tells the story of a man with the clout to call in favors for friends in the industry, able to secure a potentially career-making break for Hannah writing for a pop star (Alexandra Daddario) in need of authentic lyrics, while being completely unable to help himself. As Hannah works through the bureaucratic red tape to place Theo in a care facility, the film relays a fragile situation in the most impressive of ways, with Pegg redeploying the same instincts that make him such a great comic actor to make Theo’s capricious mood swings feel genuinely dangerous and hard for Hannah to read, while Temple shows considerable poise in guarding against opening herself up completely to him.

Still, everyone involved in “Lost Transmissions” do just that on the screen and following a well-received premiere of the drama at the Tribeca Film Festival, O’Brien spoke about marshaling the resources for her first feature, getting just the right wavelengths going between her two leads to portray the mercurial relationship between Theo and Hannah and capturing a sense of place as much as the people she trains her lens on.

How did this come about?

It’s inspired by some similar events that I went through with a friend of mine in Los Angeles, when he went off his medication for schizophrenia and a group of us were trying to get him help. I’m not myself a musician, but a lot of friends are in the music scene and for some reason, I’ve always gravitated towards musicians – my brother’s in punk rock bands and I shot some concert films in New York when I was here at Columbia University for film. It always seemed tangential that music should factor so heavily into my life, but then I lived this story that I knew that I had this really universal experience that many people shared with me that they’ve had, so I really wanted to tell it and felt that I could use all that those relationships in the music scene to portray it accurately.

The sound becomes so crucial to this film in illustrating the relationship between the two characters. Was it in mind from the start?

It came very early on. The title was actually something that I have thought of probably in the very beginning stages of writing the script, which was really helpful because in a weird way the titles have the DNA for the rest of the movie. Having that title really helped me understand the tone and the identity for the film, and “Lost Transmissions,” for me is about what Theo does as a producer and sound waves and how that feeds into his delusions. Also, you have two people functioning on these different wavelengths and they’re just missing each other and getting lost in the ether, so with the sound design, I worked with Brent Kiser from Unbridled Sound, who really understood what I was trying to go for with creating that atmospheric ambiance.

Schizophrenia is an overload of stimulation that your brain can’t process and a lot of details are heightened, so I wanted to have that play naturalistically in the beginning, but as Hannah dives more into Theo’s world and tries to understand him more – because I think these things are kind of infectious when you’re around people who are going through this, we started to key those up a bit and really bring out those sounds and incorporate them into the score. There’s a lot of back and forth between [score and sound design].

How do you think of Simon Pegg to play Theo?

I really was just a fan of his films and I really love the way he understood how to play humor and different tones of humor. This particular film calls for such a nuanced touch with the way humor plays. These situations are very serious and very traumatic for the people experiencing at the time and wrought with drama, but then with a little bit of space and stepping back, you see that they were absurd and there’s humor to that. It was also a coping mechanism for me growing up in my family because my grandmother was schizophrenic. So I thought that he’s such a fine actor and has such a depth of talent that I wanted to explore his more dramatic side with this role and it was something that encompass all his whole range of his skill set.

At the premiere, Juno suggested he was on the project for a while. Could you build the part around him?

It did go through a couple of rewrite phases during that time. Because it’s an indie film and it traverses a lot of Los Angeles, I wanted to show all the different kind of social strata that’s present in Los Angeles, from these record label high-rises and celebrities’ houses in the Hollywood Hills to Skid Row, so we were just trying to make the script concise and doable. That’s mostly how it was changing. But we definitely had lots of conversations throughout that process.

Simon and I had known each other for a while [before shooting] and then Juno came on and she’s an incredible burst of energy. You know, open the door and she just throws up her arms and it’s a big hug. You knew immediately that this was going to be great and we spent two weeks rehearsing just at my house in Silver Lake, so it was a really intimate environment – very safe, very protected and out on my deck overlooking Silver Lake. Most of the time, we’d just end up shoot the shit talking, making jokes and being like, “We’ve got to get back and focus, “but they did have instant chemistry. That friendship that you see on screen is very real. I got very lucky in the people that I got to make my first film with.

Was there anything that you see during that process you could incorporate into the film?

It was a constant thing of seeing what worked for people and what didn’t. I’m a really firm believer that your actors are a real barometer of where there might be script problems because they’re the ones living it emotionally, so if there’s something that they’re not connecting with or they’re not feeling is authentic, you have to listen. So there would just be small dialogue changes here and there, but that was a process that I’m very open to.

That opening scene is amazing and sets the tone for the film where it’s incredibly intimate, the camera is seemingly able to go anywhere in the room and it feels largely improvised as Theo’s singing on the spot, but it can’t possibly be. What was it like creating that environment?

That was a fun scene to shoot that day. That house and the way that Arnau [Valls Colomer, the cinematographer] lit it with his neon lights created this very pastel, warm vibe. And we actually worked with Marius De Vries, our music director who’s incredible – he was the music director for “La La Land” and composer for “Moulin Rouge” and all these major films – and he really came in with all these ways of how to instruct them to play and for us to shoot and record, so that they felt very comfortable. He and Liz Kinnon, the piano instructor he works with, trained both Simon and Juno so that they could really feel like they knew the movements and not just how to play, but how to the piano with ease, so it really helped us be able to show that authentically and still allow them to not be too focused on it – to still be interacting with the room and perform.

Was there a particularly crazy day of shooting?

I broke my arm. That was a pretty crazy day. The day after we finished with the the psychiatric hospitals in Pomona, I got on my grip’s skateboards after wrap and just took a tiny little tumble and caught myself funny. But I showed up the next day to our car stunts with my arm in a sling. [laughs] So that was the only thing that went wrong. Everything else was just the smoothest shoot imaginable.

Even the chase through Griffith Park at night, leading up to the observatory?

Yeah. It’s movie magic, finding the right place, but the observatory for me is one of those really iconic L.A. places and it fit so well into Theo’s delusions. I had friends who had houses right below that area and they helped us by letting us to show up in their yards and shoot at night. It was helpful to shoot in our hometown where we had a lot of friends with places that they let us shoot in.

Was directing a feature what you thought it would be or different?

Before you do it, it just seems so massive. I tried to prepare myself mentally and to get on a routine, like making yourself into Rocky going into these things, but I really just found it’s just taking one step at a time and putting one foot in front of the other. There’s a billion things that have to get done and you just get go down the checklist and get them done. Once you get to the other side, you’re like, “Oh, films are doable. They’re a lot, but there’s a method and and you can get it done.” That was a big take away, feeling how possible films are to make.

What’s it like premiering at Tribeca?

It feels great. It’s such a strange experience getting to this place and then it is hugely vulnerable because you’re putting a part of your soul out there, the most intimate parts of you for a lot of people to see. But honestly, one of the most gratifying experiences I’ve had has been doing these interviews and talking to people such as yourself because these ideas that have been in your head and that you’re hoping would just spark conversation or thoughts in somebody else are being picked up on. We’re having this conversation, and that to me has been the most rewarding experience so far.

“Lost Transmissions” will screen at the Tribeca Film Festival on May 3rd at 9:30 pm at the Regal Cinemas Battery Park.