It’s only teenage wasteland, as Pete Townshend once sang. “How I Live Now” is a meticulously observed, rapturously directed account of World War III and its aftermath as seen from the point of view of a spoiled young woman. The movie’s pretty fascinating before it goes bonkers.
There is talent involved. Director Kevin Macdonald made “The Last King of Scotland” and specializes in hallucinatory hyperrealism. Saoirse Ronan, once the spooky little tattletale of “Atonement,” has added this role to the roster of damaged adolescents she’s collecting on her way to adulthood: the kid assassins of “Hanna” and “Violet & Daisy,” the regretful vampire of “Byzantium,” the alienated split personality of “The Host.”
Their skills combine to give “How I Live Now,” adapted from a popular young adult novel by Meg Rosoff, a feverish urgency that sustains it for an hour or so. Daisy (Ronan) arrives at the rambling country home of her British cousins in a jangle of nerves and hostilities. She’s over from the States for the summer and isn’t happy about it, popping meds to keep the voices and body issues at bay and clamping headphones over her ears to shut out the world.
The cousins — gangly Isaac (Tom Holland) and wild-child Piper (Harley Bird) — plus the kid next door, Joe (Danny McEvoy), think she’s simply daft. The movie’s unstated position is that what’s wrong with Daisy is America, and that a girl’s best remedy for that would be oldest cousin Edmond (George MacKay), who whispers to hawks and wears wool knits with strapping sensitivity.
The children’s mother and Daisy’s aunt (Anna Chancellor) is some kind of high-level peace negotiator who, after one sympathetic chat with her niece, jets off to avert Armageddon. Easier said than done. Up to this point, “How I Live Now” has been in a constant macro-lens swoon over the idyllic state of nature, but now it steps back to imagine how it would feel if a nuclear device exploded, say, 150 miles away. The seismic detonation is awful; the sense that the children have been abandoned by civilization more awful still.
After days of fending for themselves, they’re taken in by the forces of the military government, which itself is under assault from attacking forces. Daisy and Edmond are separated, vow to reconnect at the homestead, and “How I Live Now” plunges into a sort of apocalyptic Incredible Journey, the American girl and her little cousin Piper crisscrossing England to find what’s left of home.
On one level, the movie doesn’t sugarcoat what social breakdown looks like. There are characters who don’t make it to the end credits, and a scene in which Daisy stumbles into a nightmare of pillage and murder is truly terrifying. Like Michael Haneke’s devastating 2003 “Time of the Wolf,” “How I Live Now” asks a Western audience to imagine the dreadful things that happen to “other” cultures — genocide, mass rape — happening to us. It walks its coddled heroine and its audience up to the very lip of the abyss.
And then? Unlike Haneke’s film, it backs down. As Daisy makes her pilgrim’s progress across a fallen England, shedding her adolescent entitlement as she goes, “How I Live Now” becomes less a vision of apocalypse and more an empowerment manual for teenage girls. I don’t want to spoil the finale, but it’s fairly lunatic in its sense of romantic sacrifice and fulfillment, as though the movie were an end-of-the-world daydream in Daisy’s head as she sits through a particularly boring chemistry class back home — or as though Haneke had handed “Time of the Wolf” off to Nicholas Sparks and the editorial board of Cosmo. Their message: Nothing improves a girl’s low self-esteem like the end of the world.