Audiences can always count on actor Rose Byrne to deliver, no matter what kind of show or movie she’s in.

She can make you laugh (“Bridesmaids,” “Neighbors,” Apple TV+’s “Platonic”). She can give you a good fright (“Insidious,” “28 Weeks Later”). She can pump you up with pure popcorn entertainment adrenaline  (a “Star Wars” or an “X-Men” movie).

Whatever it is, she’ll nail it.

“There’s so much fun to be had in genre (filmmaking),” Byrne said in San Francisco recently.

But in director Mary Bronstein’s new film “If I Had Legs I’d Kick You,” a powder-keg of a drama with sharp comedic edges, the versatile Sydney-born star roots through an entire actor’s toolkit in a performance that might just nab her an Oscar nomination.

With the camera often a mere inch or two from her face, Byrne is on fire in every scene as unraveling Long Island mom and therapist Linda, a woman on the verge hammered with one stressor after another, from caring for a daughter with a feeding tube, to dealing with a craterous hole in her ceiling that has forced a move to a motel, a demanding absentee husband a couple of clients with issues that become her own, and even her own put-upon, disapproving therapist (Conan O’Brien).

Rose Byrne attends the premiere for “If I Had Legs I’d Kick You” during the New York Film Festival earlier this month. (Andy Kropa/Associated Press) 

It’s a visceral experience that grabs you by the throat from the start.

“If I Had Legs I’d Kick You” opens Oct. 17 in the Bay Area.

From the first read of Bronstein’s screenplay, which is based partially on her personal experiences, Byrne knew she had to play Linda.

“(Mary) just lit the paper on fire when she wrote the script,” Byrne said during a visit to the Mill Valley Film Festival, where she was honored with a Spotlight award for her performance in the film.

“The screenplay is very reflective of what you see. It was a very visual, descriptive movie (and) already kind of mapping out the more ambiguous kinds of ideas that she deals with. … And I just loved it. I devoured it. And thought, ‘Where do you begin with this character because it’s so purely internally from her perspective?”

The gutsy opening shot of the film — with Byrne’s face filling the frame while Linda’s vocal daughter (the character is never seen) can be heard off-camera — lets you know you’re in for something different.

“It’s an interesting film because it sort of starts and you’re dropped in such a hot situation,” Byrne said. “It’s like a quarter way through that it kind of catches up with you, ‘Oh, I’m not going to be let out of this perspective. It’s quite a wild decision from a filmmaker’s perspective I think and such a vision on her part to do that. But there’s so much nuance and humor in the way she’s chosen to direct it.”

One of Bornstein’s boldest decisions was not to show Linda’s daughter on camera (we only hear her voice) as well as to not give her a name. Byrne explains Bornstein’s rationale behind that.

“As soon as you see a child on screen, rightly so, your sympathies go with the child. And (Mary Bronstein) takes that choice away,” she said. “So you are forced to reckon with this woman who is a challenging character making choices that are hard to watch but kind of choices she has to make because otherwise you’re not sure what she would have chosen to do if she didn’t kind of act out like this in many ways.  So it’s been wild to hear people’s responses and experiences watching the film.”

Due to the Jenga-like tower of precarious issues, the act of parenting becomes more arduous and challenging for Linda — a chore even.

“I’m a parent (Byrne and husband, actor Bobby Cannavale, have two children) and it is the joy of (parenting) that is so extraordinary and profound and how revealing it is on your own limitations. But Linda is a caretaker at this point. A lot of people can relate to that because you could be a caretaker for a parent, for an elderly friend or for an animal. For anything, but that pressure that you have to manage is a feeling you can relate to.”

Given that she had to maintain a high level of intensity throughout the 27-day shoot, it might seem like it would be hard for an actor to leave a character such as Linda behind.

“It was,” Byrne acknowledges, adding but: “I’m pretty much church and state. I try not to bring my work home. I have small kids (Rocco and Rafa). They don’t care. It’s very refreshing and they’re not interested in my navel gazing.”

That said, Byrne said there were days “when you come home and your adrenaline is through the roof” and that she did have some separation anxiety from Mary Bronstein and that “holding on to it so tightly and then having to let go was a bit strange.”

In addition to her numerous comedic performances, she’s been in such action/fantasy films as “Star Wars: Episode II — Attack of the Clones” (and she recently said in an interview she’d be happy to rejoin the “Star Wars” universe), “X-Men: First Class” and “X-Men: Apocalypse” amongst others.

With “If I Had Legs I’d Kick You,” Byrne noticed people wanting to put the film into a particular genre silo.

“Some people have said it’s just a nerve-jangling comedy and other people have said it’s a body horror and others have said it’s a dramatic take on motherhood with searing Lynchian undertones. So no one can pin it down and it’s awesome. Because Mary is kind of defying it all, very punk.”

The same could well be said of Byrne’s career, which will bring her to the New York theater scene for the Noel Coward comedy “Fallen Angels” in spring 2026. (Byrne attended Australian Theatre for Young People when she was 8).

“I haven’t done a play for about five years,” she said. “I think it’s such a different muscle. … It really requires a different performance in many ways. There’s the obvious innate theatricality of it and how to do that.”

She readily admits she’s in awe of Broadway performers. Her husband Bobby is appearing currently on Broadway in “Art,” opposite James Corden and Neil Patrick Harris and costars in the upcoming “Blue Moon.”

“I always do feel like a bit of an interloper in the theater,” she said “I’m still that student that didn’t get into drama school. So I’m like ‘Am I allowed to do this?’,” she adds, laughing.

She said she is scared about doing it.

“But that’s why I do it. If it was easy quote unquote, then why do it? That’s pretty dull.”