26 Oktober 1967
Susy Hendrix is pas getrouwd en recent blind geworden. Ze wordt geterroriseerd door een stel misdadigers. Zij zijn in haar appartement op zoek naar een pop waar heroïne in verstopt zit.
In a Montreal apartment, a woman named Lisa (Samantha Jones) waits for an old man to sew bags of heroin into the cloth body of an old-fashioned doll. As she leaves the apartment with the doll, we see the man watching her leave, then dialing someone on the phone. Lisa takes the doll with her on an airline flight to New York City, but when, on disembarking, she sees a man watching her, she becomes worried and gives the doll for safekeeping to a man she'd spoken with on the plane, professional photographer Sam Hendrix (Efrem Zimbalist Jr.). The man who'd been watching Lisa then roughly escorts her away. Later, when Lisa calls Sam about the doll, Sam and his wife, Susy (Audrey Hepburn), who is blind from an auto accident, are unable to find it.
Small-time con artist Mike Talman (Richard Crenna) and his partner Carlino (Jack Weston) arrive at a basement apartment where they expect to meet Lisa, their former partner in crime. No one is home, and unbeknownst to the two, the apartment is not Lisa's, but Sam and Susy's. Harry Roat, Jr. (Alan Arkin), the man who met Lisa at the airport, arrives at the apartment to persuade Talman and Carlino to help him find the doll. After discovering Lisa's body hanging in a garment bag, Talman and Carlino want to make a quick exit, but Roat points out that they have left their fingerprints all over the apartment, while he has made sure he has touched nothing but the arms of the rocker in which he was sitting, which he then wipes clean. Roat is then able to prevail upon the two to help him dispose of Lisa's body, explaining that he'd caught her going into business for herself. He also tells them about the heroin-stuffed doll and offers to cut them in if they help him find it. While the men are meeting, Susy comes home briefly and is observed by the men, who stay silent and undetected.
The next day, Susy's neighbor leaves for the weekend, and Sam leaves on a wild goose chase photography assignment (in reality set up by Roat) to Asbury Park, New Jersey. Once Susy is alone, the criminals begin an elaborate con game. In order to gain entry into the apartment, Mike poses as a friend of Sam's, Carlino poses as a policeman, and Roat poses first as an old man and then as the man's son. Using first an innocuous story about Sam and the doll, then a darker one implying that Lisa has been murdered and that Sam will be suspected, the men persuade Susy to help them find the doll. Mike gives her the number for the phone booth across the street as his own after falsely warning her of a police car stationed outside.
During this time, Susy has grown suspicious of Carlino and Roat, and Gloria (Julie Herrod), a girl who lives upstairs and helps Susy with errands, has been going in and out of the apartment, sometimes without Susy's noticing that she is there. After Mike leaves, Gloria sneaks into the apartment carrying the doll, which she had taken to play with. She tells Susy that there is no police car outside, and Susy discovers the doll. Wanting to confirm her suspicions about Carlino and Roat, Susy tells Gloria to go home and watch the phone booth. If a man goes into it, Gloria is to phone Susy, let the phone ring twice, and hang up. Gloria tells Susy that she can signal her by banging on the pipes.
On Carlino's next visit, after he calls Roat at the phone booth, Gloria sends Susy the telephone signal, and she sends the signal a second time after Susy calls Mike to tell him she has the doll. Finally realizing that Mike, too, is a criminal, Susy hides the doll. When he walks in with Carlino and Roat following quietly, she tells him that the doll is at Sam's studio. The three leave after Roat cuts the telephone cord.
Susy sends Gloria to the bus station to wait for Sam. When Susy discovers that the telephone cord has been cut, she prepares to defend herself by putting the criminals in the dark along with her, breaking all the bulbs in the apartment's light fixtures except for the one in Sam's photography 'safe light'. She also pours a chemical into a bowl. When Mike returns, he realizes that she knows the truth and demands the doll, but she refuses to cooperate. Mike has spent more time than the others with Susy, and he has come to admire her for her quiet strength and ability to stand up to the three of them, despite her disability. He admits to her that he and his confederates are part of a criminal plot and that Sam, as Susy suspected, is innocent of any involvement, while Roat is a particular danger. Mike assures Susy that she does not need to worry about Roat, as he has sent Carlino to kill him. However, having anticipated their plan, Roat has killed Carlino instead, and, as Mike prepares to leave, Roat stabs him in the back.
Intent on acquiring the doll, Roat chains the door shut in the dark apartment, pours gasoline on the floor, and sets a piece of newspaper on fire. Susy finally agrees to give him the doll, and he puts out the fire. Susy throws the chemical at Roat's face and desperately unplugs the 'safe light' while Roat throws his knife at her, which misses and embeds itself in the wall as the apartment is plunged into darkness. Roat lights a match but hastily puts it out when Susy, having found the gasoline, starts splashing it in his direction and onto him. But the battle ends when Roat obtains light by opening the refrigerator, whose door he props open with a rag in the hinge. Susy, hearing the refrigerator come on, and weeping as she realizes that she has lost the battle, pulls the doll out from its hiding place and hands it to him. While Roat cuts open the doll and gloats over the treasure inside, Susy is able, unnoticed by him, to arm herself with a large kitchen knife. Roat then pushes Susy towards the bedroom and pins her to the wall. Susy stabs Roat who collapses, seriously wounded. She flees but is unable to escape through the chained door. She stumbles across the floor toward the kitchen window to scream for help, but Roat unexpectedly leaps up from the floor and grabs her ankle. Screaming, Susy wrenches free, but the dying Roat doggedly pursues her, using the knife with which she stabbed him to drag himself across the floor. Susy conceals herself behind the refrigerator door, and Roat dies as the police arrive with Sam and Gloria.