It’s doomsday with an upside

In the grimly involving “These Final Hours,” the fiery effects of a crash-landed asteroid are wiping out the planet and heading for their last devastating stop: Australia. And there’s nothing anyone in the coastal city of Perth, where the film is vividly set, can do but wait. Oh, and go literally crazy.

At the center of the mayhem is James (Nathan Phillips), a broad-shouldered everyman with responsibility issues. In the beginning, he leaves the bed of pregnant girlfriend Zoe (Jessica De Gouw) to visit a second squeeze, the shrill Vicky (Kathryn Beck), who’s busy partying like it’s 2099 with her mohawked brother (Daniel Henshall) and a bunch of last-blast orgyists.

En route to the bacchanal, James must fend off a swath of anarchic locals, who’ve turned into weapon-wielding, homicidal — or suicidal — maniacs. He ends up rescuing an endangered child, Rose (Angourie Rice), and against his better judgment, he takes her along on what becomes an increasingly desperate if cathartic journey.

Writer-director Zak Hilditch, with a strong assist from cinematographer Bonnie Elliott (who’s bathed her frames in a kind of eerie sulfuric yellow), has crafted an urgent yet strangely simple and humanistic doomsday scenario. If how some folks here choose to spend their last moments alive — getting lost in sex, drugs and booze or merely finishing a jigsaw puzzle — may not feel all that, well, earth-shattering, there’s a raw authenticity to it all.

Phillips, an Eric Bana-like hunk, brings requisite intensity and gravitas to his role as the reluctant hero, with young Rice showing grace and maturity as the equitable, resilient Rose. Intriguing stuff.

“These Final Hours.” No MPAA rating. Running time: 1 hour, 27 minutes. Playing: Laemmle’s Town Center 5, Encino. Also on VOD.