Serge Gainsbourg did nothing to help reverse the French stereotype. He smoke, drank and sleazed heavily, and with an arrogance and aloofness that earned him adoration in his homeland, but alienated most people outside France. His life certainly had its rock-star crises, not least the moment when he told Whitney Houston on live television that he wanted to fuck her (YouTube it). Yet Gainsbourg: Vie Heroïque forgoes the histrionics of the conventional rock biopic: unlike Ray or La Vie en Rose, it doesn’t squeeze every last drop of melodrama out of its subject’s life. First-time director Joann Sfar skirts around the break-ups with Brigitte Bardot (Laetitia Casta) and Jane Birkin (Lucy Gordon), and ends the narrative before the songwriter’s last erratic years of alcoholism. Instead, he preserves the cool and charismatic Gainsbourg (Eric Elmosnino) in a sequence of scenes that show him singing, smoking, drinking and sleazing.

But are we watching the real Gainsbourg? Significantly, Sfar opens the film with his Jewish upbringing in Nazi France. The young Lucien Ginsburg (a strong Kacey Mottet Klein) reacts to the anti-Semitic authorities with characteristic defiance and impudence – he is first in line to collect his star of David badge, whereupon he boasts to the officer that he has a Nazi friend at the art academy; but he is dogged by an awareness of his Jewishness, and the outsider status that it entails. This self-consciousness continues into adulthood, even after Lucien adopts the more stage-friendly name Serge Gainsbourg: in his boldest move, Sfar creates a sinister puppet-like alter ego with exaggerated “Jewish” features, and has it follow the adult Gainsbourg for most of the film. Gainsbourg therefore cannot escape his self-image of the “ugly outcast”, and instead decides to filter it into his rock-star persona (which he names Gainsbarre). We see Gainsbourg irreverently recording a reggae version of “La Marseillaise”, and the controversy that it provokes: the songwriter, though thoroughly French, is keen to remain on the fringes of society.

The clue is in the film’s subtitle: “a fairytale by Joann Sfar”. As he admits (in a quote that appears before the end credits), Sfar is “more interested in Gainsbourg’s lies than his truths”. This affords the former graphic novelist a certain stylistic, as well as narrative, flexibility; hence the alter ego’s features, the animated opening credits, the Moulin Rouge hues. The film is the better for it. But more importantly, the quote betrays Sfar’s real interest: in Gainsbourg as a persona. Gainsbourg the arrogant, aloof star is constantly tested against reality – his Jewish heritage, his ugliness, his general lack of self-confidence – but the persona is only reinforced as the film progresses, until the puppet-like alter ego disappears around forty-five minutes before the end. What’s left behind is a rock star caricature who wears shades indoors and is almost too cool to have sex anymore. A product of Gainsbourg’s lies?