The premise of the new film “Shiva Baby” sells itself: While begrudgingly accompanying her parents to a shiva, the Jewish mourning ritual, a college student encounters not only her ex-girlfriend, but also her sugar daddy. Filmmaker Emma Seligman ran with the classic advice to write what you know, combining the experiences of sugar babies she knew at New York University with her own memories of what it was like to grow up in a Reform Ashkenazi Jewish community in Toronto.

“It’s funny, there’s just the same amount of bragging and nosy questions,” she says of the shivas she has attended. “I initially thought of it as a bar joke — a girl runs into her sugar daddy at a shiva, and what happens after that? But as I was making it, I realized I was putting a lot of my insecurities into it, especially the way I felt when I was approaching graduation. All the pressure I felt.”

Those feelings were fresh for Seligman, 25, who directed her debut feature just a couple of years after graduating from college. Released Friday on-demand, “Shiva Baby” is a pressure cooker of a movie from the moment aspiring artist Danielle (Rachel Sennott) and her parents (Fred Melamed and Polly Draper) arrive at the shiva, where she is accosted with questions about her future: She plans to attend law school in the fall, right? Oh, wait, no, that’s Maya (Molly Gordon, playing Danielle’s ex).

From retro camera zooms to frames slightly curved in a “funhouse way,” the film’s stylistic choices capture Danielle’s claustrophobia — further projected to the audience through a horror-esque musical score by composer Ariel Marx. Seligman knew she wanted a sparse sound that relied on the palette of traditional Klezmer music “without it being ‘Fiddler on the Roof.’ ” To Marx, that meant setting brass and woodwinds aside to focus on strings.

“She wanted the score to really, really punctuate the anxiety, but nothing else,” Marx says. “That’s a fun task as a composer because what we ended up with was all about torturing the instrument.”

The frenzied score suggests as much, though Marx insists her violin and cello survived unscathed. At times joined by percussionist Sam Mazur, whose drumming contributes a low rumble, Marx built the sound from scratch. The original “Shiva Baby” short, Seligman’s college thesis that premiered at South by Southwest, lacked music, and she hadn’t added a temporary score to the feature before bringing Marx onboard. Even the anxiety-ridden references Seligman provided — Trey Edward Shults’s “Krisha” and the Safdies’ “Uncut Gems” among them — focused on the narrative more than sound.

In hindsight, Marx draws parallels between the textural quality of her score and that of the thrillers “Under the Skin,” “Hereditary” and “Midsommar.” Its few moments of quirkiness recall the work of composer Jon Brion, specifically for “Punch-Drunk Love.” But while working, Marx continually returned to Danielle’s frame of mind. What would establish the character’s audacious spirit as she arrives at the shiva just hours after leaving her sugar daddy’s apartment with a sparkly new bracelet? What would broadcast her panic upon seeing him (Danny Deferrari) enter the house, later joined by the wife (Dianna Agron) and child she didn’t know he had?

“Once we were shooting the scene where [Danielle] is looking over at Kim and Max’s baby for the first time, getting a good look at them and the baby is crying, I realized … the dialogue was background noise and the scene was about her really understanding what this baby meant in Max’s life,” Seligman says. She thought, “Music would be awesome to heighten this moment.”

Marx chose to layer trembling strings over the baby’s wails, adding rough plucks — the instrumental torture mentioned earlier, as she pulled the strings so they’d snap back against the fingerboard — to punctuate Danielle’s tense movements. There’s a snap as she lifts her chin to get a clearer look at Max and Kim, and another as Maya’s mother breaks that concentration to call her over.

“These are generally not sounds that you play and use for a beautifully soloistic violin passage,” Marx says, laughing. As Danielle departs her comfort zone, so, too, did Marx’s technique. She experimented with circular bowing for musical cues gluing the others together, a method utilizing the “warm, less defined color” from bowing over the fingerboard as well as the “grating, distorted sound” from near the bridge. It resulted in a hypnotic, off-kilter lull, Marx says, almost like the electricity flowing through Danielle’s veins.

This sound envelopes Danielle toward the end of the film, disheveled and emotionally overwhelmed as she approaches Kim and Max. The camera shakes as it narrows in on her face, the score nearly overpowering her uncomfortable chitchat with Kim about how “female entrepreneurs do it all.”

The compounded pressures Seligman felt at this point in her own life gave her a panic attack, she says. The “old traditional standard” of finding a stable job with a stable income contrasted with her desire to also be “an independent, sexually empowered young woman who doesn’t care what anyone thinks of her, who breaks the mold and doesn’t have a traditional career.”

She adds of the film, “I think I just wanted a window into the horror of being a young woman.”

correction

A previous version of this story contained an error regarding Emma Seligman's upbringing. She grew up in a Reform Ashkenazi Jewish community, not "reformed."