Erupcja      Director: Pete Ohs Cert: 12AGenre: DramaStarring: Charli XCX, Lena Góra, Will MaddenRunning Time: 1 hr 12 minsFew pop stars have straddled mainstream domination and experimental tendencies quite like Charli XCX. From the toe-tappers Boom Clap and I Love It through the abrasive, futuristic bops of Pop 2 to the internet-cultivated self-awareness of Brat, she continually reshapes her sound.Unsurprisingly, her blossoming sideline in film is equally varied. Set over a long weekend in Warsaw, the slight, appealing romantic drama Erupcja follows three people caught between the lives they have fashioned and the ones they imagine they might still reclaim.Charli XCX, aka Charlotte Aitchison, plays Bethany, a Londoner visiting Poland with her boyfriend, Rob (Will Madden). His carefully composed itinerary for museums, restaurants, sightseeing and a marriage proposal quickly implodes. Rob imagines the holiday as a first step towards a shared future. But Bethany’s mind is elsewhere – specifically, with Nel (Lena Góra), a florist and old friend whose appearance reawakens an unresolved romantic connection.The emerging American director Pete Ohs, working from a collaboratively developed script, allows the story to drift around Warsaw’s underground art scene. A romantic mythology that Nel and Bethany have invented, noting volcanic eruptions coincide with their encounters, doubles as an illustration of lives periodically destabilised by buried feelings.The film’s greatest asset is its freewheeling atmosphere. Shot, edited and directed by Ohs, Erupcja unfolds through fragments, chance encounters, wanderings and passing moods. Jacek Zubiel’s cryptic Polish-language voiceover echoes the folksy ruminations of Sam Elliott in The Big Lebowski, while bursts of music and saturated colour cast a dreamy spell.[ Tuner review: At 88, Dustin Hoffman still has it opposite Leo Woodall in old-school thrillerOpens in new window ]The Polish capital thrives on screen as a vibrant crush of bars, impromptu exhibitions and late-night carousing. Following on from impressive turns in 100 Nights of Hero and Sacrifice, Charli XCX continues to demonstrate real screen clout, perfectly capturing Bethany’s uncertainty. Góra brings warmth and mystery to Nel, while Madden gives the film its emotional anchor as a man gradually excluded from a story he had imagined as his own. At just 71 minutes, Erupcja is more sketch than statement. But its potent snapshot of roads not taken stays long after the credits have rolled.In cinemas from Friday, June 5th[ The Moment: Charli XCX mockumentary relies on damply written stereotypesOpens in new window ]