American thriller in which a young woman realises the man following her everywhere, who she has deemed to be a stalker, is actually a product of her imagination. When Sawyer Valentini (Claire Foy) reaches out to a mental health institution to receive treatment for her delusions, she unwittingly admits herself as a patient and is forbidden from leaving. Determined to prove that she is clinically sane and is being held against her will, Sawyer makes many attempts to get out by different means. Enlisting the help of her mother, she asks her to come to her aid and force the facility to let her out. But when she stops receiving communication from her mother, is her one last hope of being set free now gone?