La Vie en Rose is a seductive musical biographical film with a transcendent performance by Marion Cotillard as the legendary French chanteuse Edith Piaf. But before we get to that, let’s tackle a pair of tough questions: Who was Edith Piaf, anyway? And why should we care?

Writer and director Olivier Dahan’s nonlinear biopic addresses both these questions, of course, but let’s pretend we’ve never heard the name Piaf before. First, listen to the voice: sharp, clear, piercing, with amazing tremolo, high-pitched and yet emotionally profound, deep as the ocean.

It doesn’t take much imagination to picture a love story—a tragic one—unfolding in her songs. We get the same sense of backstory in Piaf’s vocals that we do in the singing of Billie Holiday, as if the life she lived and the life she sang about were the same. Piaf lets everything out, but not the way American Idol contestants do. Her approach is the opposite of studied and mechanical—it sounds completely unrehearsed, as if she were warbling in the street, cold and shivering, dreaming of a bowl of soup and the boyfriend who stood her up.

Born in Paris to an Italian street-singer mother and an itinerant performer father, Edith lives with her grandmother, a bordello madam in Normandy. Director Dahan and director of photography Tetsuo Nagata paint the entire first half of her life in shades of gray.

Piaf earned her street cred with the French working class the hard way: circus hired girl, harried street singer in Place Pigalle where a club owner plucks her off the corner, puts her onstage, and dubs her La Môme Piaf—her real name was Edith Giovanna Gassion. The Little Sparrow kills them and eventually moves from Montmartre to international success, but she never cuts her connection to the gutter. In fact, for all the scenes of Piaf conquering the crowds in grand concert halls, the diamante brute’s best performances take place drunk in the dives, surrounded by pimps, whores, and assorted riffraff, her real public.

Cotillard, who had a featured role in A Very Long Engagement, captures the tentativeness and vulnerability of Piaf’s appeal as she cringes before an audience. This girl of the slums is frail, haunted, scared, alone, out of luck, strung out, exhausted, and head over heels in love. Even at the height of her success, she doesn’t look happy. Her joy is always extreme, her lows bottomless. Maybe that’s why despite her celebrated romance with boxer Marcel Cerdan (Jean-Pierre Martins) Piaf’s closest personal relationship was with her street partner Momone, artfully imagined by Sylvie Testud.

Except for one or two rousing scenes of impromptu songs performed in her own voice, Cotillard lip-synchs to Piaf’s recordings, heavily weighted toward the ones that were hits in the United States. The film spends too much time in New York and Hollywood, then tries to make up for it by having Piaf express her disdain for an iffy review in the American press: “They think I’m sad. I don’t get them, and they don’t get me.” But times change, and the strong voice of a poor, disadvantaged woman may have its uses, and La Vie en Rose, for all its romantic, theatrical grimness, is a good place to start.

LA VIE EN ROSE  ( * * * )

Directed by Olivier Dahan. • Starring Marion Cotillard, Sylvie Testud and Emmanuelle Seigner. • PG-13, 140 min. • At the Osio Cinemas.