LONDON — London-based sales agent Protagonist Pictures is unveiling Kevin Macdonald’s “How I Live Now” to buyers at the Cannes Film Festival next week.

Alliance Films and Momentum Pictures have acquired rights in Canada and Blighty respectively in a pre-emptive deal made ahead of the market.

Pic, based on the tome by Meg Rosoff, follows a 15-year-old girl from New York who is sent to England one summer to stay with cousins she has never met. After initially having difficulty dealing with her relatives, she soon adjusts and falls in love with her cousin, but the affair is affected by the outbreak of a fictionalized war, which separates the whole family.

Story, which is at script stage, is adapted by scribes Tony Grisoni (“Red Riding Trilogy”) and Jeremy Brock, who penned “The Eagle” and “The Last King of Scotland” for Macdonald.

Pic is produced by “The Last King of Scotland” producer Charles Steel and Alasdair Flind, John Battsek and Andrew Ruhemann and is co-developed and co-financed by Film4.

Macdonald most recently directed Bob Marley docu “Marley,” based on the late reggae legend, for which sales agent Fortissimo Films secured a raft of distribution deals in Berlin’s European Film Market.

Also on the Protagonist slate for Cannes this year is docu “The Imposter,” helmed by Bart Layton, which is in post-production.

Docu follows the true-life tale of a young Frenchman who convinces authorities and a grieving family that he is the 16-year-old boy that went missing in Texas three years earlier.

“Imposter” is produced by Dimitri Doganis, while John Battsek (“One Day in September,” “Restrepo”) and Simon Chinn (“Man on Wire,” “Project Nim”) are exec producers, alongside A&E IndieFilms and Film4.