The Knife (1918)

Kate Tarleton grows up on a Southern plantation and becomes engaged to her guardian, Dr. Robert Manning, a famous surgeon. When Robert, Kate, and her younger sister Mary Lou visit New York, where the doctor wishes to conduct medical experiments, the superstitious Kate goes to the home of a fortune-teller named Stella Hill. Stella, whose principal business is white slave trafficking, drugs Kate and forces her to work in a "den of vice," run by Stella and her accomplice Jimmy Bristol, where she contracts syphilis and goes insane. Robert, Detective Ellis, and a lawyer named Billy Meredith rescue Kate, who recovers her sanity but remembers nothing of her bondage. Robert uses Stella and Jimmy in his experiments and through them discovers a cure for Kate's illness. District Attorney Scott is questioning Robert about the propriety of his experiments when Kate enters and sees Jimmy. Her memory suddenly returns, and she narrates her story to Scott, clearing Robert's name.