In 1967 Santa Monica, California, young doctor John Form gives his pregnant wife Mia a rare vintage porcelain doll in a white wedding dress for her antique collection. That night, Mia wakes to horrific screaming next door at their neighbors', the Higgins family. John rushes over and finds the Higgins couple brutally murdered. As John calls the police, two members of a Satanic cult break into the Forms' house, attacking Mia and stabbing her abdomen before police officers arrive and shoot the male attacker dead.
The female intruder locks herself in Mia's nursery, cuts her own throat, and dies holding the porcelain doll, allowing a drop of blood to fall directly into its glass eye. Police identify the killers as the Higgins' estranged daughter Annabelle and her boyfriend, both members of the occult Disciples of the Ram cult. Miraculously, Mia and her unborn baby survive the trauma, and John throws the bloodstained doll directly into the trash before they move into an apartment in Pasadena to start over.
Following the birth of their baby daughter Leah, Mia begins unpacking their belongings, only to find the discarded porcelain doll inexplicably sitting inside one of the moving boxes. Unsettling events rapidly escalate inside the apartment: sewing machines run on their own, phonograph records spin backwards, and mysterious fires erupt. Mia befriends Evelyn, a local bookstore owner grieving the death of her own daughter, who warns her that the cultists were attempting to summon a malevolent entity.
Mia encounters an aggressive demon in the apartment basement that demands a human soul. Father Perez, a Catholic priest, attempts to take the doll to church for consecration, but the demon attacks him on the steps, gravely injuring him and taking the doll back. Father Perez warns John from his hospital bed that the demon does not want the doll; it wants baby Leah's soul, which can only be surrendered through a voluntary sacrifice.
John and Evelyn rush back to the apartment to find Mia trapped inside a telekinetic storm. The demon hides baby Leah and attempts to force Mia into committing suicide by jumping out the window to save her child. Just as Mia prepares to jump, John and Evelyn break through the locked door. Evelyn steps forward, confessing her lingering guilt over the death of her own child, and takes the doll, jumping out the high window to her death. Leah reappears unharmed, the demonic presence dissipates, and the Forms escape the nightmare.
