The Seventh Victim (1943)

When her older sister Jacqueline disappears, Mary Gibson is forced to leave her private school and decides to travel to New York City to look for her. A bit naive and out of her depth, she is not sure how to go about finding her. Eventually she meets Gregory Ward, her sister's husband, and a mysterious psychiatrist, Dr. Louis Judd, who claims to know of Jacqueline's whereabouts. What she doesn't realize is that her sister became involved with devil worshipers who now want to eliminate her for revealing their existence.