Diane Sherman gives birth to a premature baby who is kept under careful watch in an incubator, surrounded by the hospital staff. Years pass and Diane builds a quiet life in Pasco, Washington, with her now-teenage daughter Chloe. Chloe lives with a host of health challenges—arrhythmia, hemochromatosis, asthma, diabetes—and relies on a wheelchair for movement. She is homeschooled by her mother, spends hours tinkering with electronics and circuit boards, and dreams of going to college, though Chloe’s applications have largely gone unanswered.
One ordinary morning, Chloe glimpses something unsettling hidden in a grocery bag: a prescription bottle bearing Diane’s name, but when she investigates further, the label has been plastered over with her own name. Her curiosity leads her to a puzzling clue about a drug called Trigoxin, yet the house has no internet access, keeping her in the dark about its true nature. A phone call to a random number the next day provides a fragment of truth: the drug is a heart medication in the form of small red pills, and the mystery deepens.
Later, at a cinema, Chloe feigns a trip to the restroom and slips to a nearby pharmacy to uncover more. The pharmacist reveals the green pills are Ridocaine, a substance approved for dogs but capable of paralyzing a human if ingested. Chloe panics, and Diane’s sudden intervention ends with her sedating Chloe to take her home, but the seeds of doubt have been planted.
Back in Chloe’s room, an escalating series of restraints and power plays unfolds. The door is locked from the outside, and Chloe’s attempt to break free leads her to the roof, then to Diane’s bedroom where she shatters a window with a soldering iron. An asthma attack follows, and Chloe barely makes it back to her inhaler. Her automated wheelchair ramp is disabled by a cut power cord, forcing Chloe to manage an even more dangerous escape—dragging herself down the stairs and discovering, through a small movement of a single toe, that some feeling has returned after not taking Ridocaine for several days.
A chance encounter with a postal worker named Tom becomes a lifeline as he volunteers to help, but Diane intervenes, slipping away with Tom’s body as Chloe watches in horror. The basement becomes a stage for shocking discoveries: childhood photos showing Chloe walking, a death certificate for a girl named Chloe who died shortly after birth, and a clipping about a hospital baby theft. Hidden college acceptance letters surface, revealing a hidden life Diane has kept secret from her daughter. A confrontation follows: Chloe accuses Diane of poisoning her and lying about her health, while Diane insists that every action was meant to protect Chloe.
In a tense turn, Diane produces a homemade neurotoxin, claiming it will erase the memory of what’s true. Panicking, Chloe crawls away and locks herself in a closet, and in a desperate act, swallows a bottle of organophosphate, spurring Diane to rush her to the hospital.
Chloe awakens in a hospital bed, intubated and frail, with doctors reluctant to discharge her until a mental health assessment is completed after what is deemed a suicide attempt. A nurse brings a crayon and paper, and while Chloe tries to write, a code blue sounds, and Diane infiltrates the ward armed with a handgun. She binds Chloe to a wheelchair and tries to escape as security closes in. In a dramatic moment near a staircase, a guard shoots Diane in the arm, sending her tumbling down.
Seven years pass, and Chloe’s life has moved forward with a measure of independence. She walks short distances with a cane, has built a life with her husband Ara and daughter Annie, and works as a prosthetist. She reveals that Annie has a certain fondness for her grandparents, suggesting a reunion with her birth parents. Before leaving the facility, Chloe discreetly pockets three Ridocaine pills she has smuggled out, and she looks back with a quiet resolve as she speaks a final, ominous line to the future: open wide.
