Scotland's film-making Macdonald brothers have a busy week.

While Trainspotting producer Andrew is involved with Sunshine On Leith, director Kevin has helmed How I Live Now. The latter is quite an original proposition - ostensibly a teen romance, but set within a near-future milieu that is disturbing, even harrowing, and with a central character who takes a while to warm to.

New York teen Daisy (Saoirse Ronan) is sent by her father to the English countryside and her dead mother's family. It's an odd time to despatch her, on the brink of a third world war, and her hurt is unconcealed. With piercings, torn leggings and attitude to burn, Daisy couldn't be less friendly to her hosts. Her cousins, however, are sweethearts, intent on winning her over. Just as they succeed, war breaks out. And their bucolic idyll is torn asunder.

Despite Macdonald's muscular style, for a time the film feels inconsequential, until the hardships of the war begin to bite, the story becomes harsher, and Daisy grows up fast, driven by the need to keep her new-found family intact.

Daisy doesn't feel like a stretch for Ronan, who could be the Jodie Foster of her generation. A more notable performance comes from George MacKay - having a red letter day given his role in Sunshine On Leith - as Daisy's cousin and romantic interest.