The Underpass follows a young woman named Fiona, a struggling music student, who starts working as a part- time carer for Ms. Venable, an ailing old woman. Soon after meeting Ms. Venable at her mausoleum-like terrace house in Melbourne’s leafy north, Fiona is asked to complete a bizarre task by the old woman in exchange for money. Cryptic instructions lead her to a desolate location late at night where she witnesses something frightening…