Let Her Out (2016) on Netflix

Plot summary

Helen works as a bike courier. Her mother tried to kill her before she was born, twenty-three years ago, and Helen remains psychologically damaged. A traumatic head injury in an accident puts her in the hospital, where a tumor is found in her brain. The tumor is what remains of a twin that vanished in the womb. After her release, Helen suffers blackouts and hallucinations. She sees dark visions, hears disembodied voices, and encounters a strange young woman. Her best friend Molly is also in danger. Helen's actions become vicious and she barely remembers them. She cannot tell what is real, and something inside her cracked psyche wants out.