In a post-apocalyptic England overrun by flesh eating ‘hungries’, a 10-year-old human/hungry hybrid with a genius IQ (newcomer Sennia Nanua) may be the key to a possible cure.

Based on the novel by Mike Carey, this horror thriller departs from zombie-movie convention by making us root more for one of the infected than the human survivors.

That’s not to say Gemma Arterton’s nice teacher, Glenn Close’s driven scientist and Paddy Considine’s hard-nosed army sergeant don’t earn our sympathy, too.

Yet as this group flees across the countryside towards possible safety in London, it is Nanua’s smart but feral girl who emerges as the story’s ambivalent heroine.

Director Colm McCarthy’s film is plodding and clunky in places, but it does deliver some genuine chills, startling images – look out for the fate of London’s BT Tower – and some weighty moral issues to ponder. This film premieres on Sunday 9 July.