Doctor Leonard Chaney, an ophthalmologist, is driven to find a cure for blindness after his daughter, Nancy, loses her sight in an automobile accident; the doctor was driving the car. When Chaney invites his colleague, Doctor Dan Bryan, Nancy’s fiancé, to dinner, Chaney’s assistant, Katherine, drugs Dan’s cocktail. Showing Dan his work, Chaney explains his interest in corneal transplants and his experimentation with full eye transplants using dogs. Chaney tells Dan he wants to transplant the healthy eye of a living human into another person to restore Nancy’s vision. Dan begins to feel the effects of the drug and realizes that Chaney intends to use him as the donor. Once Dan loses consciousness, Chaney performs the operation with the help of Katherine. Sometime later, when the bandages are removed, Nancy’s vision is restored. Chaney receives a phone call from the police and reports he has not seen or heard from Dan. When Nancy says she wants to see Dan, her father replies that it is not a good idea, but she drives to his home anyway to surprise him. Dan’s landlady informs Nancy that Dan has been gone for quite sometime. Meanwhile, at the hospital, Chaney deflects a question from a colleague about Dan’s whereabouts and begins to share his new findings. However, he is interrupted by an emergency call from home; Nancy’s vision failed while she was swimming. After examining his daughter, Chaney is baffled. Downstairs, in the lab, Katherine is accosted by Dan, now blinded and in a cell, but she escapes. Later, after determining that he needs a new donor, Chaney picks up a hitchhiker. He takes the young woman to his laboratory and performs another transplant, but the operation is unsuccessful. Next, he interviews two young women under the pretense of hiring a full-time nurse for Nancy. When he finds the right candidate, he performs the operation again; however, Nancy’s vision remains impaired and he goes in search of another pair of eyes. Chaney meets a real-estate agent and makes her the next donor. The operation is initially a success, but after a few days, Nancy’s vision again fails. With the scars around her eyes growing with each surgery, Nancy tells her father she has had enough and he sedates her. Katherine tells the doctor that he needs to dispose of the blinded donors, who he has been imprisoning in the basement of his house. However, Chaney replies that he intends to help them once he restores Nancy’s vision. After another transplant fails, the doctor turns his attention to children, theorizing that he needs young eyes. In a park, he meets a young girl named Libby and entices her to come with him by promising her a trip to Disneyland. When Libby realizes they are not headed in the right direction, she tries to escape and the doctor gets into a minor collision with another car. Libby flees. The other driver, Al, and another man, Georgio, follow Chaney home. He offers them $1,000 to forget the incident and they agree, but before they go, he offers them drugged wine, giving him two more donors. After their eyes are removed in the cell, Al reacts violently. Dan restrains Al and convinces him to use his strength to help the prisoners dig through the wall. Meanwhile, Chaney finds a vagrant and offers him a decent meal, but the man steals his wallet. When Chaney returns home, Katherine informs him that one of the female patients died and she had to remove the body. Downstairs, another of the female donors escapes through the freshly-excavated hole. Chaney and Katherine capture her, but the real estate agent also escapes. Before Chaney reaches her, she is struck and killed by a car. The coroner informs the investigator, Detective Simon, that the woman’s eyes were removed prior to the accident and adds that the leading authority in the area is Doctor Chaney. Detective Simon asks Chaney to examine the body to determine why the woman’s eyes were removed. Chaney is evasive, but agrees. He reports that it is not unheard of for both eyes to be removed, due to syphilis, cancer, or some other cause, but it is rare in someone as young as the victim. He offers Simon a glass of wine, but the detective declines. Later, Chaney promises the donors that he will restore their vision once he helps Nancy. As he is speaking, Dan reaches through the bars of the cell and grabs Katherine, choking her to death. Chaney then transplants her eyes into Nancy. As the doctor buries Katherine’s body outside, Nancy awakens, her vision restored. She goes downstairs looking for her father and is horrified when she stumbles upon the cell. When the doctor returns, he finds Nancy upstairs in her room, claiming she cannot see. She sneaks away and goes downstairs to give Dan the key to the cell. Chaney enters the laboratory and the donors push him into the cell, where Al gouges out the doctor’s eyes with his fingers. The captives escape from the doctor’s home.