Widowed mother Holly is radically tested when her teenage daughter Betsey experiences a profound enlightenment and insists that her body is no longer her own, but in service to a higher power. Bound to her newfound faith, Betsey refuses to eat but loses no weight. In an agonizing dilemma, torn between love and fear, Holly is forced to confront the boundaries of her own beliefs.

A mother and her three daughters — romantic Bee, sensible Evie, and child of nature Daisy — occupy the titular glass building, which has been completely sealed off to protect its occupants from a dementia-inducing toxin called the Shred that’s poisoning the air outside. Fearful of becoming like the lost souls who wander the abyss outside, the family keep a grasp on their past by performing sacred rituals. When Bee breaks the rules and lets an injured stranger into their midst, the family dynamic is shattered forever, as hidden truths upend the illusions the women have worked so hard to protect.

Follows a woman desperate to escape her town, she meets a stranger who promises a romantic escape, but it results in deceit, mistrust, and violence.