In most disaster movies, the disaster is the star. Hurricane. Tsunami. Megalodon. Godzilla.

Not so in "Leave The World Behind" (now on Netflix), director Sam Esmail's ("Mr. Robot") tense reworking of Rumaan Alam's 2020 bestseller by the same name.

Here the disaster is never well defined, though its effects – from Wi-Fi outages to deer infestations to beached cargo ships – stir up mounting levels of paranoia in a vacationing couple (Ethan Hawke and Julia Roberts), their teens (Charlie Evans and Farrah Mackenzie) and a mysterious duo (Mahershala Ali and Myha'la) who appear late at night in their rented home's doorway.

"It’s a disaster movie that reorients you away from the disaster and towards the disintegration of these six characters," says Esmail. "In some ways, it betrays the genre, but that made me more excited about doing it."

Esmail spoke to USA TODAY about reworking elements of the book to fit his film, how Roberts was his first choice for prickly Amanda, and getting script notes from former President Barack Obama, who helped back the film through his and Michelle Obama's production company Higher Ground.

The biggest differences between the film and book versions of 'Leave The World Behind'

Alam's novel is anchored to a mysterious blackout in New York City that causes George, or G.H. (Ali), and Ruth (Myha'la) to go back to their fancy home on Long Island, which Amanda (Roberts) and her family have rented.

Esmail says he has long been fascinated with cyberattacks ("they're out there and they're mystifying") and decided to weave that into his movie as an added layer, which results in eerily garbled smartphone news alerts and other discomfiting plot points.

But the biggest change was made to the character of Ruth, who in the book is G.H.'s wife. In the movie, Ruth is now his snarling daughter. "Because this subject of alienation is so timely, I felt we needed that Gen Z and millennial point of view, not just for her commentary on the crisis but also for the friction with Amanda," he says.

Imagine Julia Roberts as unpleasant and racist and you have her 'Leave The World Behind' character

Amanda's unrelenting suspicion of G.H. and Ruth keeps the movie on a perpetual boil. But the motivations behind her sentiments can be seen two ways, at times unflinchingly racist (how can these Black people be the owners of this ultra-fancy vacation home, she suggests) and in others borderline reasonable (why are these strangers showing up at our door at nearly midnight claiming there's a blackout?).

Roberts walks that tightrope delicately, as Esmail had hoped. "She was my only choice for this role," he says. "Julia is the Michael Jordan of actors, so why not go to M.J. if you need to pull off something insane like this movie. Amanda is so prickly and so flawed, so you need great talent but also that undeniable charm for the audience to stay with her.

"I think her America’s Sweetheart persona is why this was exciting," he continues. "After test screenings, some people said they could see her (character's) point of view about not wanting to let these strangers in so late."

Yes, Barack Obama really gave notes for scenes in 'Leave The World Behind'

Esmail says Obama did leverage his White House years in helping fine-tune some of the technological disaster elements of the film, reassuring the director that some of the more dystopian implications of his movie were less than likely.

Instead, Esmail says, Obama spent most of his time drilling down on the character interactions that crumble away during the crisis.

"Here we have one of the most brilliant minds on the planet making sure we kept focusing on this cautionary tale about mistrust," he says. "He's a movie lover and a fan of the book, so what he really wanted to emphasize with me was hitting on this point about how lack of empathy that can happen in a crisis and what that means for us all."