Marion Cotillard and Brad Pitt are to star in a war thriller.

The 39-year-old actress is in talks to join the 51-year-old hunk in the upcoming romantic drama, set during World War II, which will be directed by 'Forrest Gump' and 'Back to the Future' filmmaker Robert Zemeckis.

The as-yet untitled film has been penned by screenwriter Steven Knight - who has previously worked on 'Dirty Pretty Things' and the TV series 'Peaky Blinders' - and will follow the two characters who play assassins, who fall in love while trying to assassinate a German ambassador.

However, the movie is set to feature a major twist, with the Hollywood Reporter stating the couple marry, with Brad's character later discovering his wife is a double agent working with the German government meaning he also has to kill her.

Further cast details of the film are yet to be revealed, although shooting is scheduled commence next year in London, Canada and Casablanca.

The period drama follows other films shot by Brad also set during World War II including 2014's 'Fury' and 2009's 'Inglourious Basterds'.

Meanwhile, Marion has recently completed filming alongside Michael Fassbender in Justin Kurzel's movie adaptation of 'Macbeth', which received rave reviews at Cannes Film Festival last month.