Cannes 2013: Inside Llewyn Davis, review Dir: Joel and Ethan Coen; Starring: Oscar Isaac, Carey Mulligan, Justin Timberlake, John Goodman, Garrett Hedlund. 105 min. Inside Llewyn Davis, the new film from Joel and Ethan Coen, is a hymn to squandered potential, missed opportunities and unsung genius. That's a subject far removed from the experience of the Coens themselves, who, since the release of their debut feature Blood Simple in 1984, have had critics and audiences yodelling enthusiastically of their brilliance. Well, at the Cannes Film Festival on Saturday night, the yodel went up once again. The Coens" new picture is a perfectly pitched melancholic comedy set in the New York City folk music scene of 1961. It has an acidically funny Kafkaesque streak that recalls the brothers" 2009 coming-of-age drama A Serious Man, although it is more of a piece with their 2000 masterwork O Brother, Where Art Thou?, from its magpie borrowings from Homeric myth to its seriously groovy soundtrack. Their film strikes the near-impossible balance of being uproarious entertainment in the moment and a profound philosophical treatise in retrospect, and you drift out of the cinema on an intensely weird cloud of existential angst and toe-tapping acoustic guitar music. Oscar Isaac stars as Llewyn Davis, a struggling folk singer who plays thinly attended gigs at The Gaslight Café, a club in the city's West Village. But despite his low profile, he is extraordinarily talented, which the Coens establish in a blissful, pared-down opening sequence in which he performs the old Dave Van Ronk number "Hang Me, Oh Hang Me." Llewyn is effectively a Bob Dylan manqué, right down to the familiar Welsh twang of his name - and the film goes on to suggest that, with a little more luck and slightly better timing, he might have won the Dylanesque degrees of success and acclaim that he so hungrily craves. Instead, he sleeps on friends" sofas, tramps the cold streets of Manhattan without a sensible coat, and treats other performers at the club with florid contempt. Two of them are Jim and Jean, a singing duo (and married couple) played by Justin Timberlake and a hysterically irritable and flossy-haired Carey Mulligan. Early in the film, Jim wins Llewyn a session gig on a novelty record called "Hey Mr Kennedy," and the song exudes so much guileless joy it raised a cheer at the critics" screening. An odyssey of sorts unfolds when an audition takes Llewyn west to Chicago, and he hitches a ride with an ogreish jazzman (John Goodman) and his beat poet "valet" (Garrett Hedlund). Later, the return trip involves a heartbreaking decision about which fork in the road to take. Throughout his journey, we increasingly feel that Llewyn is trapped in an unwinnable game of catch-up with fate, and the sense becomes so gnawing that it threatens to take off your leg. An ingenious running joke about a runaway cat hints that a more conventionally heroic narrative may be unfolding elsewhere: meanwhile on-screen, the New York streets look as grey as gravestones, and a chill wind tickles almost every shot. This is instant A-list Coens; enigmatic, exhilarating, irresistible.