On screen and in her music, actress-singer Charlotte Gainsbourg is a conundrum, open to emotions yet never completely unravelled.

On her fifth album - and her first in seven years - she has parlayed her contrarian sensibility to devastating effect in an elegiac exploration of grief.

Rest, written in the wake of the death of her half-sister, photographer Kate Barry, who fell from her fourth-floor Paris balcony in 2013, digs in deep but does not wallow.

Instead, Gainsbourg distils pain via an urbane palette of disco synths and dancey beats like emollient cream over still sore wounds. The surface is smooth and chill, but it takes someone patient to espy the cracks.

The title track, co-produced by Guy-Manuel de Homem-Christo, one-half of the Parisian house duo Daft Punk, is undergirded by a somnolent bassline, as if a cool party is taking place next door.

Above the bassline, she coos her part-French, part-English confession as minor keys echo. "We're floating in the moonlit sky/I'm finding I can fly/So high above with you," she sings, presumably addressing Barry.

Crucially, the song and album title is a bilingual pun too.

In English, it means sleep or eternal rest (as in "rest in peace"). In French, it means "stay". "Restes avec moi," she sings in the chorus, which translates to "stay with me".

This double-play is a perfect trope for her barely contained sanity, an allegiance to decorum despite terrible losses.

French producer SebastiAn, who worked with Frank Ocean on last year's Blonde album, draws out tension and the gap between public and personal spheres.

Kate, a disco chanson whispered, feels unbearably private, an unloading from one sister to another. The more uplifting Songbird In A Cage, written by Paul McCartney, fits into this narrative too, a life cycle of expirations and resurgences. She half-speaks the lyrics - "Songbird in a cage/Someone that takes pity/Opens up the door" - over rhythms that trip and race.

Freedom and imprisonment, celebrity and surveillance - these are flip sides of each other, which the singer surveys.

Small wonder she would take refuge in make-believe, the power of the imagination.

Sylvia Says is a jaunty romp lathered with slick synths and hip-swinging beats, as Gainsbourg switches between heaven and purgatory: "I shut my eyes and all the world drops dead… I lift my eyes and all is born again."

Her clear-eyed acceptance of life's blessings and cruelties is realised in the single Deadly Valentine, a Moroder-esque riff on "wedding vows with an offbeat tone".

"From this day forward, for better, for worse, until death do us part," she intones. Everyone dances, none the wiser, slowly wound up in the mortal coil.