Bette Davis stars as Mrs. Elliott, the reclusive mother of sculptor Jeffrey Elliot (Ted Bessell), who hires college student Peggy Johns (Sian Barbara Allen) to care for him and his elderly mother at their mysterious mansion. As Peggy navigates her new job, she uncovers dark secrets about Jennifer, Jeffrey's sister, whom he believes is psychotic and living in a secret apartment above the garage. When Peggy finally meets Jennifer, she attempts to stab her to death before being thwarted by Mrs. Elliott, who later reveals that Jeffrey murdered his sister years prior, using her as material for one of his sculptures.