It’s no secret that motherhood isn’t all cuddles and giggles, but these two new thrillers take things a step (or several) further. They plumb the darker side of maternal instincts via unnerving, slow-burning stories of mothers, daughters and the secrets and lies that sometimes bind them.

Long-buried secrets boil up to the surface in Kate Riordan’s The Heatwave, an unsettling and claustrophobic thriller set in the south of France during a scorchingly hot summer.

Sylvie Durand has pushed her family home, La Reverie, firmly out of mind and memory for 10 years—but in 1993, when she receives a letter notifying her of arson at the empty property, she must return. She does so with great reluctance and deep dread, but her beloved 14-year-old daughter, Emma, is thrilled. She’s always been curious about the place where she was born and lived until she was 4, when her parents divorced after her older sister Elodie’s death at 14.

As Emma explores the crumbling yet grand manse, complete with sparkling pool and rickety barn, Sylvie struggles with her emotions. She’s been keeping secrets about their family for so long, she’s having a hard time feeling safe in the place that was the setting for long-ago traumas. It doesn’t help that the house feels haunted by Elodie, an arrestingly beautiful and dangerously manipulative child whom Sylvie likens to “those Manson girls . . . sloe eyes opening to reveal the void.”

Riordan moves Sylvie’s narration between past and present in the form of an apologia to Emma, slowly and ominously revealing details about the family as she invites musings on the mutability of memory and the ever-fascinating question of nature versus nurture. The novel also turns an unblinking eye on what it’s like to desperately want a mutually loving relationship with your child, and the guilt that arises when it becomes clear that’s likely impossible.

Forest fires flicker on the horizon, the threat edging closer and closer, as Sylvie attempts to sell the house and flee once again, before the truth is no longer able to be denied. The Heatwave is an excellent example of why the saying “you can’t go home again” rings so true. It’s a discomfiting, suspenseful tale that’s sure to delight fans of Lionel Shriver and Daphne du Maurier, as well as of Riordan’s previous book, 2015’s Fiercombe Manor.

Discomfiture takes a different sort of turn in Little Disasters by Sarah Vaughan, author of the bestselling Anatomy of a Scandal. In every group of mom friends, there’s always one—the mother who seems to take everything in stride, remaining endlessly unflappable and upbeat no matter what challenges come her way. Here, that woman is Jess Curtis.

Jess is a well-off stay-at-home parent of three—two school-age boys and 10-month-old baby Betsey—who’s always made motherhood look easy (especially to said mom friends Liz, Mel and Charlotte), even without much support from Ed, her workaholic husband. And so Liz, a senior hospital resident in pediatrics at St. Joseph’s Hospital in West London, is shocked when she’s called to the ER to consult on an infant with a suspicious head injury and realizes the baby is Betsey, brought in by a shifty and evasive Jess. The sequence of events Jess provides doesn’t make sense, but she’d never harm one of her children . . . right?

Vaughan’s tense, twisty drama is told from various points in time, from three points of view: Liz, Jess and sometimes Ed, all of whom realize they don’t know each other as well as they’d thought, all of them afraid of what will be revealed in the search for the truth. From the start, it’s clear that Jess has been suffering from depression and anxiety, exacerbated by sleep deprivation: “The walls push in; the heat bears down and the noise—the terrible crying that has been going on for three hours—engulfs her. . . . She does not know how much more she can bear.”

Suspicion is cast on various players as social workers and police try to separate fact from falsehood, and Liz must contend with her persistent unease as she struggles to reconcile her seemingly conflicting roles of doctor and friend. She also must deal with traumatic memories triggered by the goings-on, including the realization that her own mother, an often cruel alcoholic, may be keeping terrible secrets of her own.

Little Disasters’ slow-reveal rhythms make for a squirm-inducing and thought-provoking examination of friendship, marriage and motherhood.