The Cow Winona Ryder Dermot Mulroney

AUSTIN, Texas — A May-December couple heads to the woods for a romantic getaway, only to discover the Airbnb they rented was double booked. That’s the deceptively simple premise behind “The Cow,” a thriller starring Winona Ryder and Dermot Mulroney that premiered at this year’s SXSW.

“Something we were trying to play with was what kind of movie are you even in,” Director Eli Horowitz said Tuesday night during a question-and-answer session following one of the film’s screenings. “Are you in a horror/thriller movie? Are you in kind of like a mumblecore rom-com?”

The answer is both. “The Cow” opens with Ryder and her cradle-robbed love interest (played by John Gallagher Jr.) driving to a cabin in the woods for a tryst that quickly goes awry. A disturbing young couple is already staying at the property, but the four of them decide to share the space for the night.

Director Eli Horowitz takes questions from the audience at SXSW in Austin, Texas. (Spectrum News/Susan Carpenter)

Newcomer Brianne Tju steals the show as an assertively sexual man stealer, hitting on Ryder’s boyfriend as the couples kill time with a late-night board game. When Ryder wakes up the next morning and discovers her boyfriend and the younger woman are no longer there, she presumes she’s been dumped.

And that’s when the story begins to twist in surprising directions, as Ryder contacts the cabin’s owner to get the young woman’s phone number and starts falling for the age-appropriate homeowner. Nothing is as it seems, however.

Inspired by his experience as a fortysomething grappling with the choice of clinging to youth or embracing older age, Horowitz co-wrote the script with fellow podcast creator Matthew Derby. Horowitz created the “Homecoming” podcast — a scripted thriller starring Catherine Keener, David Schwimmer, Amy Sedaris and David Cross that was turned into an Amazon Prime Video series starring Julia Roberts.

“The Cow” is his directorial debut. Recognizing he was out of his depth, Horowitz said he read books on how to direct and chatted with friends who had directed to learn everything he could.

“Some of that preparation was actually useful, and some of it just sort of made me feel not as terrified to do it,” he said.

Horowitz wasn’t sure why Ryder agreed to star in the film, but she was the first to sign onto the project.

“It was strange to me also,” said Horowitz, who sent the script to the “Stranger Things” star through her managers hoping she would not only like the story but would respond to its setting in the place where she had grown up. Horowitz also joked that the first line of his pitch was leveraging his surname, which is the same as Ryder’s birth name.

“I still don’t really understand why she signed on,” Horowitz said, adding that Ryder was just wrapping up “Stranger Things” and had only been in one other movie in the last 20 years.

“The Cow” was shot without any rehearsals because all of the actors were busy and there wasn’t enough time, so Horowitz had  Zoom meetings with the actors individually to prepare them.

An independent film shot with “limited resources,” Horowitz said he used his personally owned cabin in the Northern California redwoods as the main location. The Airbnb theme in the film is based on his lived experience. He rents the cabin “and was always afraid of accidentally double booking it,” he said.

“The Cow” was one of several celebrity films making their debuts at this year’s SXSW. “The Lost City” starring Sandra Bullock and Daniel Radcliffe, “The Unbearable Weight of Massive Talent” with Nicolas Cage and “Everything Everywhere All at Once” with Michelle Yeoh and Jamie Lee Curtis also headlined.

Horowitz decided to premiere the film at SXSW because “it seemed so fun. It seems like such a great way to make the movie tangible,” he said. “Movies like this, often they’ll just go to a streamer and then people watch it and you can’t ever feel it. So it’s really exciting to be a part of this.”