Secret Ceremony (1968)

Leonora, a prostitute, mourns the death by drowning years earlier of her daughter. She encounters a strange waif-like girl, Cenci, who bears a strong resemblance to her lost child. Cenci is herself struck by the great resemblance of Leonora to her own mother, whose death the mentally unstable Cenci has been unable to accept or even acknowledge. The two women quickly develop a symbiotic relationship, moving in and out of the illusion that each is the lost loved one of the other. The complicating factor is the arrival of Albert, Cenci's stepfather, whose incestuous attachment to her may well be the cause of her mind's unbalance. With Albert's arrival, no one in the strange trio is safe.