Justin Timberlake and Marcus Mumford announce track for Coen brothers film Justin Timberlake has confirmed that he will collaborate with British musician Marcus Mumford, frontman of Mumford & Sons, on a song for a new film written and directed by Joel and Ethan Coen. Inside Llewyn Davis tells the story of a singer-songwriter as he tries to break into the New York folk scene in the 1960s. It stars Oscar Isaac, a rising star familiar from Drive, as Davis. Timberlake plays Davis's musical rival Jim Berkey, married to Jean, played by Carey Mulligan (Never Let Me Go, An Education). Mulligan's real-life husband Mumford met Timberlake during the film's production. Timberlake told London radio station Capital FM: "I did work with Marcus Mumford on the soundtrack, so I became very good friends with them." He said the unlikely collaboration with the folk singer was a result of the film: "I don't know any other world where we would have the opportunity to collaborate like that but it was so much fun. So not only will that be a great movie, but the music to it will be fantastic. Mumford & Sons won two awards at this year's Grammys, for best long form video and album of the year for Babel, which is in its fifth week at number one in the Billboard 200 chart. Timberlake is also starring in Runner, Runner, opposite Gemma Arterton, as a protégé of an offshore gambling businessman, played by Ben Affleck.