First things first. Those opening lines, damn. The baby is dead. It took only a few seconds. This is no murder mystery: the blurb on the cover gives away the killer. And yet, French-Moroccan author Leila Slïmani’s slim, unsettling whydunnit Lullaby has sold over a million copies.

That number will soar further – the English translation has been out for less than a month, and it is not every day that a translated book gets billed the next Gone Girl. More remarkably, this blockbuster novel also won France’s highest literary prize, the Prix Goncourt. You are not alone if you are curious about what goes into the making of a seemingly-oxymoronic literary thriller.

The story begins with a middle-class and upwardly-mobile Parisian couple’s search for a nanny after the wife decides to return to work as a lawyer. Their requirements will elicit uncomfortable (but knowing) chuckles: no illegal immigrants, not too old, no veils. Myriam and Paul Massé find the perfect nanny in the form of the prim, polite, doll-like Louise. She is perfect because she proves to be “simultaneously invisible and indispensable.”

Louise wins over the two young children, cooks fabulous meals for the parents, even mends whatever would otherwise be thrown away, bringing bourgeois order and warmth to the Massés’ chaotic home. All the while, though, the reader knows that this modern-day Mary Poppins is going to commit the horrific crime in the opening scene.

At first we only see Louise through the eyes of her grateful employers, who see her as no less than a godsend in their lives. Slïmani lets us into the nanny’s wretched world slowly, through flashbacks and vignettes narrated by people who have known her. As pieces of her shattered psyche are revealed a sense of dread begins to creep up like gas leaking into an apartment.

Cold precision

Lullaby unfolds with cold precision. Slïmani’s writing is controlled and visceral at the same time: beautiful sentences and strong images never get in the way of the story. She also paints a very different picture of the most romantic city in the world. The Paris of this novel is a fraught geography: class and race fissures run deep. An upper class woman explains that she sends her child to private school so he won’t be the only “white kid in his class” or “come home speaking Arabic.” On the other hand, a children’s park offers a symphony of babble in different languages, ephemeral phrases the kids have picked up from their immigrant caretakers, legal or otherwise. Every nanny knows that this bond with the children they look after is temporary, just like the foreign vocabulary their charges have absorbed from them.

What happens then, Slïmani wants us to ask, when a nanny decides to build a nest in this temporary abode? Louise is touched by her employers’ gratitude and their small acts of kindness towards her. But it is when she starts imagining an uninterrupted future with her employers that she begins to come unhinged.

The nanny’s final descent into murderous rage was my only quibble with the novel: after building a creeping, mounting sense of dread (there’s a particularly chilling scene involving a scrubbed chicken carcass and glasses of Fanta), the book’s final blow feels rushed and not wholly convincing.

Class politics

Reading Lullaby reminded me of Prayaag Akbar’s novel Leila, in which class and caste divisions run even deeper. The protagonist Shalini forbids her nanny from kissing her daughter, does not let her use the same dishes or cups, and berates her publicly for small missteps. She claims to be liberal but sees her servant as less than fully human. Shalini pays for her hypocrisy with her daughter.

By the standards of Indian employers, where Shalini is the norm rather than the exception, Myriam and Paul seem saintly: they share meals and wine with Louise, invite her to a family vacation where Paul teaches her to swim, even let her scold them for being indulgent and wasteful. At one point Paul, whose parents are unorthodox, admits his discomfort at being “turned into a boss” in Louise’s presence. But even this liberal bourgeois Bohemian couple struggles when the lines between employee, friend and family begin to blur. Much like Shalini of Leila, they too know nothing of the brutal hardship and abuse that marks their nanny’s life outside the walls of their home. And for all their talk of Louise being family, they do not care enough to ask.

Lullaby is a taut thriller but it is also a political story, deeply aware of class, racial and gender politics. An Elena Ferrante-like rage smoulders through the pages. For Slïmani and her creations in the novel, the world of women is the claustrophobic world of bodily emissions and clipped dreams. A new mother, with her body that “smells of sour milk and blood”, finds herself “confined to the world’s edge”, while to a new father, the apartment he returns to in the evening exudes the stench of “secretion and confinement.” The feminist knows that one woman’s escape from domestic hell can only come from another’s confinement: a working mother must hand over her home and hearth to a less privileged woman, the nanny.

It’s the sophistication of Slïmani’s prose and the moral clarity of her politics which ensure that Lullaby does not come across as a simple cautionary tale. What makes this domestic thriller particularly compelling is the dots that Slïmani leaves unconnected. For example, what does it mean for Louise to be a white woman working for a North African employer doing a job done by immigrants? How does it make her feel to give her love, her all, to another’s children when she could never love her own daughter? Slïmani is too deft to draw easy lines of cause and effect, error and punishment. The big answers, she knows, lie within a tangle of fact and feeling.

Lullaby, Leïla Slïmani, translated by Sam Taylor, Faber and Faber.