A sensational performance by Sylvie Testud is the singular reason to catch this rambling biopic of Françoise Sagan - bestselling novelist, high-rolling playgirl, multiple addict, flamboyant bisexual, monstre sacré - which plays in repertory throughout April at the French Institute's Ciné Lumière. Testud, one of France's best young actresses (also currently to be seen illuminating Lourdes as a desperate young pilgrim), takes no prisoners in her electrifying account of the writer's train wreck of a life over half a century, from the precocious literary star who stormed the world in 1954, aged 19, with Bonjour Tristesse to her death, raddled, bitter, broke and alone, in 2004.