The breathless Korean sci-fi monster movie 'Hope' leaves the Cannes Film Festival floored

But that doesn't mean that Na, a few hours before debuting “Hope,” was feeling at ease.

“I’m really nervous,” the writer-director said in an interview alongside the Cannes beach. “I didn’t imagine it would be so nerve-wracking to be honest, to the point of not sleeping.”

Na's movie, one of the most expensive Korean films ever made, certainly provides no rest. For two hours and 40 minutes, it takes a story that begins with the mysteriously scarred carcass of a dead bull and breathlessly and quite bloodily accumulates into a cosmically grand, audaciously gonzo sci-fi tale.

The headlong rush of Na’s bonkers would-be international blockbuster left Cannes alternatively awed, befuddled and thrilled. Variety's Jessica Kiang called it “hilarious, unwieldy, overlong and featuring some of the most breathtakingly elegant action moviemaking of this or any year.”

Hwang Jung-min plays the Hope police chief in a rural village whose investigation into the bull attack rapidly turns into a frantic chase, following a trail of carnage through the Korean Demilitarized Zone. He's eventually joined by another police officer (Jung Ho-yeon). Meanwhile, the chief's cousin (Zo In-sung) is following a separate set of clues into the forest.

How “Hope” gets from A to B is much of the fun. But let it be known: Michael Fassbender and Alicia Vikander play extraterrestrials.

“I wanted to talk about a story that starts off with something very trivial, and that can build to something that can impact the entire universe,” Na says. “In order to tell that story, I felt I had to incorporate aliens.”

Just how grand a scope “Hope” would encompass took some figuring out for Na. He ultimately decided he would put only part of it in the film. A sequel set in space, more centered around Fassbender and Vikander's characters, has already been written. Na warmly offered “a secret,” describing how his theoretical part two ends, before being hushed by publicists.

Na rushed to complete the edit in time for Cannes. Speaking through an interpreter, he sounded very much like a filmmaker who has for years been consumed by the possible iterations of this story. That it's taken 10 years to get here, he grants, is hard to believe.

“It didn’t feel that long to me. I only realize now that it’s been quite a journey,” he sighs. “The editing took a long time. The CGI took forever.”

For the Korean stars of the film, Na was the main attraction. Asked why he wanted to do the film, Zo answers straightforwardly: “Because it's Na Hong-jin. Nothing else.”

Jung hopes the film — which Neon will release in the U.S. later this year — will bring new audiences to the director. “He has such cool filmography,” she says. “It will be nice if he can have a much wider audience.”

Hwang, one of South Korea's top stars, is reuniting with Na after starring in “The Wailing.” Almost immediately, they started talking about another film together. Hwang was the first performer to sign on to “Hope.”

“Among the actors, we have this faith in the director that whatever movie he does, he'll do a good movie,” says Hwang before deadpanning. “But I don't think he knows that many good actors.”

Some spectacular and lengthy action sequences make up much of “Hope.” But as much as the movie is a pedal-to-the-medal ride, it's predicated on some of the weighty themes that have characterized Na's films, particularly “The Wailing.”

The genre and perspective shifts in “Hope,” from monster movie to sci-fi, go to the heart of what drove Na's largest production in the first place. For him, it all began with people’s struggle to see and understand those different from them.

“I started off with a focus on xenophobia and immigrant problems,” he says. “As I was developing the story, it became a much bigger story.”

“In any big tragedy, they don’t necessarily arise from malicious intention. It all starts with difference in perspective,” he says. “I think it’s that conflict in perspective or misunderstanding that creates these collisions. That’s what I wanted to talk about.”