“Hanna” star Saoirse Ronan is in negotiations to topline Kevin Macdonald’s “How I Live Now,” an indie drama based on the 2004 novel by Meg Rosoff.Ronan will play Daisy, a teenage girl from New York City who travels to England to spend the summer with family in the English countryside. When World War III breaks out and insurgents invade, Daisy and a younger girl named Piper must survive alone in the woods as they try to make it to safety. Jeremy Brock (Macdonald’s “The Last King of Scotland”) and Tony Grisoni wrote the script. Film 4 and Passion Pictures are producing the pic with Charles Steel and Alasdair Flind of Cowboy Films. Protagonist Pictures is selling international rights for the film, which Ronan will shoot after wrapping Andrew Niccol’s adaptation of Stephenie Meyer’s young adult novel “The Host.” Irish thesp is currently filming Neil Jordan’s “Byzantium” and will next be seen opposite Alexis Bledel in Geoffrey Fletcher’s teen assassin pic “Violet & Daisy.” Ronan is repped by CAA and Macfarlane Chard.