Director Debra Granik — whose 2010 Oscar-nominated film "Winter’s Bone" introduced the world to a young Jennifer Lawrence — is back with another indie hit, "Leave No Trace."

It's about a father — a veteran who suffers from PTSD — and teenage daughter who choose to live off the grid. Will (Ben Foster) and Tom (breakout star Thomasin Harcourt McKenzie) have lived in Portland's public parks for years, and they're quite self-sufficient — only going into town to collect disability checks and buy things they can't grow themselves.

Their idyllic life is shattered when they're discovered by social services. They're given a home, and a job on a horse farm, but they clash with their new surroundings, and they end up abandoning their home for the wild.

Granik co-wrote the screenplay based on Peter Rock’s novel "My Abandonment," which was based on an article in The Oregonian about a father and daughter who were living undetected in Portland's parks for four years.

Granik sat down with VICE News to explain how she consulted vets In Portland, to be able to put very precise language to what it feels like to have PTSD, and how it affects the families of veterans.

“The teenage children of vets don't get to just put it away. You too have a legacy," says Granik. “That person who's very dear to you is waging something inside their mind and using a lot of their energy to learn how to operate back in society after after combat.”

Granik also shared the lighter side of her production for this film: what it was like for her crew to have to wear bee costumes while filming, and the joy she found studying 4H, the national community of teens who take care of barnyard animals.

“I couldn’t imagine that it would be stirring to see a chicken ministered to, bathed underneath its wing, and to see teen boys doing that,” says Granik. “When teens are doing that, I'm all kinds of happy.”

In VICE News’ Storyboard series, creators explain the inspiration and process behind making films. This segment originally aired July 3, 2018 on VICE News Tonight on HBO.