Mother (Adrienne Pearce) and her three daughters — romantic Bee (Jessica Alexander), sensible Evie (Anja Taljaard), and child of nature Daisy (Kitty Harris) — 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. On top of their responsibilities, sentry duty and harvesting the extensive crops that keep them alive, the two older sisters must tend to their brother Gabe (Brent Vermeulen), who is unable to care for himself due to past exposure. 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 (Hilton Pelser) into their midst, the family dynamic is shattered forever, as hidden truths upend the illusions the women have worked so hard to protect.