A frustratingly not-terrible action thriller.
The director Kevin MacDonald is something of a master of applying the "you are there" approach to scenarios and settings from which most people would very gladly be spared. Whether it's falling off of a mountainside (his 2003 documentary "Touching the Void") or trying to dodge getting oneself killed by ferocious, depraved Ugandan dictator Idi Amin (2006's "The Last King of Scotland," for which Forest Whitaker won a best actor Oscar in the Amin role), MacDonald is at his best putting the viewer exactly where no one in his or her right mind would want to be.
So the fact that his latest film, "How I Live Now," adapted from a novel by Meg Rosoff, is about a band of teens and children in the British countryside trying to stay alive after London gets hit by a nuclear explosion bodes well for the quality of the film. And indeed, for much of its running time the movie is grab-you-by-the-back-of-the-neck immediate; in its last third particularly, the bite-your-lip moments of suspense and tension mount to the extent that you may well draw blood.
The terrific young Irish actress Saoirse Ronan here plays Elizabeth, who insists on being called "Daisy," and whose problem-child status is established even before the opening credits begin: The nagging voices in her head are heard on the soundtrack even as the production company logos are unspooling. Now almost 20, Ronan has gotten tall, and her lovely face is long and lean; she can imbue her disturbed adolescent character with a formidable intensity merely by cocking her head and looking down. She does a lot more of course, and her character's petulance upon being exiled from New York to Britain to stay with cousins she barely knows has a particular quality that made me wonder whether she'd boned up on the role by studying the behavior some of her peers exhibit at press junkets.
In any event, Daisy is at first very reluctant indeed to join her young cousins in their little war games or forays to a gorgeous pond and waterfall near their rambling, cozy house. The lyricism of the Wordsworth-worthy setting is underscored by a nice selection of English folk-rock on the soundtrack; but soon an ominous electronic score by Jon Hopkins replaces the sounds of Fairport Convention and Nick Drake. The only adult in the house happens to be a diplomat; she flies off for an important conference, the kids are disturbed/exhilarated by a V-formation of fighter jets, and soon after that, the news comes that London's been nuked.