Michael and Madeline Matheson Jordan Ladd celebrate a hard-won breakthrough after two unsuccessful attempts to have a child, and they enlist Madeline’s former midwife, Patricia, to oversee an unorthodox delivery that they hope will safeguard their future as a family.
One night, tragedy strikes: Michael and the unborn baby are killed in a car accident. Madeline resists induction, so Patricia allows her to carry to term. The baby appears stillborn at first, but Grace is miraculously born alive, and Madeline names her daughter with a mix of relief and fear.
Back at home, Grace’s presence brings a shocking set of signals. The infant attracts flies from a putrid scent, and she struggles to digest breast milk, repeatedly vomiting. As Madeline nurses, she discovers Grace is feeding from a breast that is bleeding, a detail that unsettles her and deepens the sense that something is terribly wrong.
Meanwhile, Vivian, Michael’s domineering mother, presses for access to Grace, while Madeline resists. She seeks help from Dr. Richard Sohn, an obstetrician she believes she can trust, hoping to gather evidence that she might be an unfit mother if Grace were to be removed from her care.
To protect Grace, Madeline continues nursing with her own blood feeding the baby, a brutal strain that drains her physically. The blood loss becomes dangerous, and she eventually lets Dr. Sohn into her house to examine Grace. When the doctor nears the baby’s cries, Madeline acts in a desperate, protective move and kills him to prevent him from taking Grace away.
Vivian arrives soon after, discovering the aftermath: Grace in her crib, the bottle of Dr. Sohn’s blood spilled on the floor, and Madeline’s desperate attempt to conceal the consequences. Vivian, shaken but determined, grabs Grace and attempts to flee, later discovering Dr. Sohn’s body as she escapes. Vivian arms herself with a hammer, but Madeline confronts her in a brutal struggle. In the climax of their confrontation, Madeline rips out part of Vivian’s throat with her teeth, leaving Vivian unconscious but Grace unharmed for the moment. Patricia arrives and ends the immediate danger by witnessing Grace drinking from Vivian’s blood, a grim confirmation of the house’s dark secret.
Some time later, Patricia drives a motor home across the desert, checking on Madeline who continues to nurse Grace. She reassures herself that as long as Madeline maintains the proper diet for Grace, they can continue feeding and raising the child. Madeline, however, reveals Grace has begun teething, and in a haunting, final image, Grace’s mutilated breast is exposed, signaling that the horrifying bond between mother and child has only grown more disturbing.
