It had been a while since Sara Shaw had been on a set for any extended period of time, though this was through no fault of her own. The impressive editor behind such films as Desiree Akhavan’s “The Miseducation of Cameron Post”and Adam Leon’s “Tramps,” she saw no need to visit the productions she worked on – in fact, doing so might compromise her objectivity once the footage reached her. However, she had gone to NYU Tisch School for the Arts with plans to get behind the camera and never got around to making her thesis film, in part because her talent for editing kept her at the Avid on a steady succession of gigs, so when the opportunity presented itself to direct a short as part of the Hello Lab series sponsored by DirecTV and Fullscreen, she said yes, but with some hesitation.

“I had some jitters about it, but I found that when I got on set, the editing I had done over the past several years had really helped me to build the muscle in my brain that helps you focus and see what you want and what you’re getting, especially in terms of performance,” said Shaw. “I just had a much better time understanding what I was doing on set after editing a bunch of films and learned a lot from the directors I worked with and I found it a lot easier in some ways, to my surprise.”

While Shaw’s professional experience makes “Tooth and Nail,” premiering this weekend as part of the SXSW Film Festival so sharp, it is her personal experience, which also contributed to why she never got around to making her thesis, that makes it so resonant, recounting how her family dealt with the news that her younger brother was diagnosed with cancer. Set in New Jersey, the spectre of death is hardly going to get in the way of the boisterous family at the center of “Tooth and Nail,” as Matt (Alex Kramer) may soon be losing his hair to chemo, but not his devious sense of humor, with a proud grit that comes with staying in the sticks whereas his sister Kate (Rebecca Henderson), who fled for the city long ago, is simultaneously appalled at his brusqueness and appreciative that it may have toughened him up for the times ahead. Still, they must get through a family dinner where although no one has ever been known for their delicacy, they still have trouble finding exactly the right words to converse, making the ones they do choose awkward in ways that can be hysterically funny or unguarded and profound, brought to life with a wonderful cast to capture this moment in time with so much history behind it, including Shae d’Lyn and Lee Wilkof as Matt and Kate’s parents and Lynn Cohen as their wily grandmother.

On the eve of heading out to the festival in Austin for “Tooth and Nail”‘s premiere (though lucky DirecTV subscribers can watch it right now here), Shaw spoke about digging deep to tell this story, how editing influenced how she worked with her cast and what it was like to show the film to her parents.

How did this come about?

It came about through my collaborator Desiree Akhavan, who made “Appropriate Behavior” and “The Miseducation of Cameron Post,” and she’s been a friend and collaborator for many years. She was chosen to be a mentor for this diversity initiative that AT&T and Fullscreen were mounting. She was tasked with choosing a filmmaker from an underrepresented group that was looking for a little boost in their career, so she gave me the opportunity to make a film. I had gone to film school and needed to still make my thesis film and thought it was a great opportunity, but I had to hit the ground running [because] I was brought into take over from someone who had previously been going to [be part of the program], but got another opportunity, so I had less time than the other four filmmakers.

I knew I had to say yes. However, I didn’t really have any idea what I wanted to do. It was a pretty stressful experience trying to figure out what I wanted to make a film about and I had all kinds of crazy ideas. I thought about adapting something. But I realized — and Desiree helped me to realize — that the most interesting story I really had to tell was about my family experience. I lost my younger brother to cancer the previous summer after battling it for several years, which was of course a horrible time for my family and for him. Losing him was really, really tough and during the time of his illness, I really saw my family undergo a huge transformation, challenged by some really tough situations and figuring out how to empathize and support each other.

I realized that’s the stuff of movies, but I wasn’t sure if I was ready to tell the story or make such a public display of such private grief. However, I just kind of didn’t have time to second guess it so much, so I kept going forward with it and just tried to figure out the best way to present it to the world and the exact story to make out of that time. A lot of it’s based on true experiences, but not all exactly how it happened. The characters are tweaked and altered to make it a compelling story.

You have a co-writer on this. Was it important to have someone to bounce off such a personal story?

It was very, very important and I was lucky to find my co-writer Amanda Verwey, who did a great job in helping me to figure out how to tell this story. It was amazing to have that perspective and also [Amanda] has great taste. I didn’t know her at all. My editing agent put us in touch and basically, I just started sending her my family’s story and all this really personal information, just hoping it would work out. And to her credit, she really wasn’t daunted by all that overflow of information and personal stuff. It really seemed like she had a lot of personal experiences that aligned with mine and she used similar experiences in her life to access this story, so it ended up being a little bit of a composite of both of our family stories.

How did you find your leads to play siblings?

I had a good casting agent, Ann Goulder, and we worked really hard to try to find the right people. Having worked as an editor and scrutinized performances and shaped them for a number of years now, I’m very picky about performance and I knew that this script was not going to work without really spot-on performances. So Rebecca, who plays Kate, was in “Appropriate Behavior,” and I’d edited her performances before and knew that she was very good, very strong actress — very smart — and she seemed to be right for the part and could get that comedic timing and tone. Through my casting agent, we found Alex Kramer, who plays the brother Matt. He came in and just gave us an amazing audition and he seemed really passionate about the part. The actors really gave a lot to it.

There’s a great scene at the dinner table that juggles a bunch of tones and is quite dynamic in part, of course, because of how it’s edited. Did coming from post-production inform what you wanted to do on the set in terms of getting that scene right?

Yeah, I think I have the capacity now to think about things in terms of what I call movie time, which is not quite real time or what’s going to exist as a pure dialogue scene. I tried to find a little bit of middle ground between the two and that capacity to understand the flow of time on screen and how to play with that is something that I think I developed a lot by editing so much. I spent a lot of time trying to figure out how that dinner table scene was going to work and I didn’t know for sure until I got into the edit room, but I wanted to have the actors to improv a bit, so I had some scripted elements for the beginning — the more comedic part of the dinner scene before things really get real and in the edit room, I was able to look through a lot of that material, figure out what I had and build something out of it.

We had great actors who were very present in the moment and were able to stay in character and respond to each other, so a lot of scenes around a table, [like outside when Matt and his grandmother] smoke [a joint], we captured in super-slow motion. And we didn’t know exactly what we’d be getting in those moments. I told the actors the action to do and they breathed life into them. For the [dinner table] scene, the beginning was partially scripted and partially improv, and because I had great actors who were really funny people, I’d have them either prelapse the dialogue with an imagined conversation leading up to [to letting the camera roll] or continue on at the end of a written dialogue blurb and they came up with some really funny stuff. [For instance] I’d say, “Let’s do two minutes about politics where you’re arguing about this!” Here’s your position and here’s your position and they’d fill in with some really great lines.

I was looking for those moments where it felt like there was real genuine connection and interaction between them. One scene that delighted me especially was the relationship between Matt, played by Alex Kramer, and Grandma, played by the wonderful Lynn Cohen, a really wonderful lady well into her eighties and still just such a talented actress and so game for anything. She and [Alex] had a really adorable dynamic where she’d just crack him up and there were times where you couldn’t really tell Alex the actor cracking up or Matt the character cracking up. That blurring of the line between someone acting in character and someone just acting in their true essence and personality is what really felt vibrant about it and what I tried to keep in the film. It was really important that [Matt] was getting his grandmother stoned in part because he wants to help her, but in part it’s because he just finds it hilarious. There was something I loved about that and that felt true to life also from my experience.

It feels so authentic. Were these locations actually familiar to you?

No, that was one thing that we really didn’t have in the budget was a location manager, so I drove thousands of miles searching for the right location. I went to all kinds of AirBNBs and ultimately we found this place that had been used in other shoots in Long Island. The story is set in New Jersey where I grew up, but it’s any sort of suburb of New York I feel and we ended up in a house that was found through one of my producer Mollye [Asher]’s contacts. The owner let us use it because she was a nice lady who was very sympathetic to our plight – she had written multiple books about the history of women in film and wanted to help and support us.

We were very lucky to find it. It was her parents’ house that was largely unchanged since the ‘50s and I was actually a little bit worried it was going to be too nice and upscale, too midcentury chic, so we ended up writing into the script a little line about how the grandmother is yelling at the father Gary [over] watching Trump on TV in his father’s house and how his father would be rolling in his grave if he heard that. Gary replies, “It’s my house now” and sort of grumbles, so it ended up being a way to explain the house and make sense in character terms, but then it also gave us the opportunity to have a good character moment between Gary and his mother.

Have you gotten to share the film with your family yet?

Yeah, my brother passed away, so unfortunately I can’t share it with him, but I think he would’ve liked it and my parents have seen it many times over now. They like it a lot and they’re proud. I didn’t show it to them until it was finished and I was very worried they might not understand or appreciate it or that they might feel in some way exposed or even exploited. So I was very nervous the first time I showed it to them and I think they were a little nervous too. I think it was an odd experience for them seeing these sort of portrayals of characters that were inspired by them and vaguely resembled them, but had some key differences. The more times they watched it, I think the more they got used to it and the more that they really felt that they could understand something about my point of view and maybe about our relationship by watching this film. It’s been a good source of processing and healing for all of us in a way. Most importantly, everyone agrees that Alex, who plays Matt, did a great job with that role, making the character very compelling and lovable while also having fun with it. That felt like doing justice to my brother who was a wonderful person and really magnetic, but was going through this horrifically difficult time. Alex really nailed it.

What’s it like getting into SXSW?

It’s incredibly exciting. I’ve been wanting to go for years, but never had an opportunity and I really couldn’t be more excited. I’m just hoping to have some conversations with people about it and hope that it resonates with people. From the people I’ve spoken to so far that have seen it, it seems like even if they haven’t had exactly this family experience, it does capture something about family dysfunction and attempts to connect during times of intense grief and struggle within a family and everybody goes through one or another form of that. Being in a generous audience with people who feel the film and are very excited to watch it and respond to it is just the greatest feeling and that’s why I think we all do this or why I do it, anyway.

“Tooth and Nail” will play at SXSW as part of Shorts Program 3 on March 10 at 5:15 pm at Alamo Lamar E, March 12 at the Rollins Theatre at the Long Center at 11:30 am and March 15 at the Stateside Theater at 4 pm.