Spoiler alert! This story includes details of the final scene of "Leave the World Behind," so stop reading if you haven't seen it yet.

Netflix's dystopian science-fiction movie “Leave the World Behind” (now streaming), based on the 2020 novel, is creepy, cautionary, foreboding and chilling.

But director Sam Esmail ("Mr. Robot") provides a poignant antidote to the haunting gloom, and he has "Friends" to thank. That’s right, NBC's hit 1994-2004 sitcom, which returned to the cultural spotlight recently because of the recent death of beloved star Matthew Perry.

"Friends" plays a pivotal emotional role in Esmail's movie, which stars Julia Roberts, Ethan Hawke, Mahershala Ali and, in a small but powerful role, Kevin Bacon. (In the mid-'90s, Roberts appeared briefly on "Friends" and dated Perry for three months.) The plot of "Leave the World Behind" revolves around a vacationing family, some unexpected visitors and a world that suddenly starts falling apart.

“The whole ‘Friends’ thing was a just passing remark, really, in (Rumaan Alam’s) book, so we turned it into a storyline,” says Esmail.

The story is this: Rose (Farrah Mackenzie), the daughter of vacationing Amanda (Julia Roberts), is constantly glued to her tablet, which she uses to stream “Friends.” She is almost finished watching the show’s final episodes when disaster strikes: Her Wi-Fi becomes glitchy.

'Friends' is 'heartbeat' of sci-fi thriller 'Leave the World Behind,' says director Sam Esmail

Rose is among the first to notice and gripe about the tech hiccup, a precursor of much worse things to come. All she wants to do is simply watch the finale, but her laments are ridiculed by her surly teen brother, Archie (Charlie Evans), who can’t believe she is so passionate about what he considers a dumb, sappy show.

Which is precisely the point, says Esmail.

“We all cope with crises in different ways,” he says. “I read the book early in the pandemic, and I remember how ridiculous it was when (Netflix's 2020 docuseries) ‘Tiger King’ came out. It was what everyone was talking about. It was absurd, and yet it brought us all together despite all our differences about the pandemic.

“So much like with ‘Tiger King,’ I felt that Rose’s attachment to ‘Friends’ was very human and comforting," he says. "In a way, that is the heartbeat of the film: Rose’s yearning to escape to that comfort zone.”

In the final seconds of the movie, Rose manages to screen the finale, and the sound of that inescapable and irrepressible "Friends" theme song – "I'll Be There For You" by the Rembrandts – fills the air.

Says Esmail, “After putting audience through all the bleakness, I wanted to end on small light at the end of the tunnel.”