Mr. Kessler (Bela Lugosi) comes downstairs and greets the butler Evans (Clarence Muse). Looking at a portrait of his wife (Betty Compson) on the wall, he is informed that dinner is served. Kessler speaks to an empty chair at one end of the table (as addressing his wife) and sits at opposite end of the table. Evans comes to serve soup to him but is told to always serve Mrs. Kessler first. He apologizes and goes to the empty chair, pretending to serve. Then looking for approval from Kessler, he returns and serves him soup. As he leaves the room he is approached by Kesslers daughter Virginia (Polly Ann Young) who asks how he is taking it. She is told he is taking it well when the door buzzer sounds. Virginia announces she will answer it. Ralph (John McGuire) enters and she tells him he was told not to come. She takes him into the library to explain, but he notices Kessler speaking to an empty chair and observes. She joins him and they go into the library where she tells him that this happens once a year. Looking up, Ralph sees the maid Cecile (Terry Walker) standing with a coat. His expression reveals recognition of Cecile. She gives the coat to Virginia, who leaves with Ralph. Cecile enters the kitchen and begins asking Evans about Ralph and Virginia. She is told to mind her business. She asks about the unsolved murders and Evans tells the gardener Jules (Ernie Adams) he opened his mouth too much. Evans takes Cecile out of the room and Jules takes something from the refrigerator and places it in a bag. Going to the gardening shed, he enters and lights a lamp. He raises a trap door and descends to a room below where Mrs. Kessler has been staying. Urging her to eat her supper, she rises and recalls a car accident, saying she cant go home. He tells her he must go home and leaves.
Jules tells his wife Mrs. Mason (Ottola Nesmith as Ollola Nesmith) that he was late because he couldnt get away from Mrs. Kessler. She insists that he should tell Mr. Kessler about his wife but he says that it would kill him. She says maybe Mrs. Kessler had something to do with the murders and that she hasnt been right since the accident with the man who was killed. He denies that, saying she is harmless and that they should never tell anyone. Then he supposes that if anyone should find out he is hiding her, they might suspect him of the murders.
Ralph and Virginia return and he bids her goodnight. Offering to put her car in the garage, he is told that Evans will do it. When Evans comes out to move the car, he sees and overhears a conversation between Cecile and Ralph. She tells him that he didnt answer her letters and calls and that he better not leave her for the Kessler girl or anyone. He tells her that he doesnt love her and that no one will stand in the way of his happiness. She threatens to tell about them and he leaves.
Virginia tells her father she is in love and that Ralph will soon ask her to marry him. Kessler congratulates her and she goes up to bed. When Evans comes in, Kessler asks about the bandage wrapped around his hand. He tells him that he hurt it putting up the car. Kessler takes him upstairs, dresses the wound and rebandages it. Kessler says he will read before going to bed. Evans retires for the evening.
Mrs. Kessler comes out of the shed and stands below his window. At the same time, Kessler knowingly rises and goes to look out the window at her below. She tells him that she cant come home, because he would kill her. He would kill anybody. A trance comes over him and when he looks again, she is gone. He wanders out in a daze and makes his way to Ceciles room, entering and removing his robe. He approaches and covers her with the robe. She screams as the radio plays.
Next morning Evans goes to her room and hears the radio playing an exercise program. He knocks repeatedly and calls her name, suggesting she can exercise in the kitchen. Getting no response, he opens the door and finds her dead. He goes immediately to inform Mr. Kessler. He tells Evans to phone the police.
Lieutenant Williams (George Pembroke) is questioning everyone about the murders. He says Cecile was killed the same way as the others with no fingerprints. The only evidence is a letter she had telling her not to see him, signed Ralph. Hearing this, Virginia is startled and says she is practically engaged to a Ralph. Asking Evans if he saw anything suspicious the night before, he hesitates and is urged by the police. He reports overhearing the conversation between Cecile and Ralph where he threatened her.
Newspaper headlines proclaim Ralph accused of murder. Ralph confesses to Kessler and Virginia that he cannot account for his whereabouts at the time of the murder.
At the trial Virginia hears testimony that Cecile was frequently seen at Ralphs apartment and that the landlady thought they were married. After several people testify, we are shown the newspaper headline saying Ralph is sentenced to death.
Virginia tells Ralph that they will appeal to the governor. When the governor refuses to help without new evidence, Ralph is executed.
The next day Evans answers the door and is startled to see a man in the spitting image of Ralph, who introduces himself and enters. Kessler and Virginia are also startled when he introduces himself as Ralphs brother Paul (John McGuire). He asks to speak to them.
Evans seems in a daze as he goes to the kitchen and asks Jules if he looks pale. He freezes and doesnt respond to the servants buzzer until Jules prompts him. As he approaches the table and is told to bring coffee, he stares at Paul until informed that he is Ralphs brother.
Paul is reassured by Kessler that he is welcome to stay there as long as he wants. Kessler goes to prepare a room for him and shows him to it.
Mrs. Kessler again comes to the window and Kessler is strangely drawn to look. Going again trance-like Kessler approaches Evans to kill him but turns away after Evans leaves the room. Instead Kessler goes to the kitchen where he finds and kills Jules.
The next morning the body is discovered by Evans who phones the police. He informs Kessler that the gardener has been murdered. The police arrive and begin questioning everyone. Told that they have a new houseguest, an officer is sent to retrieve him. Paul comes downstairs and is directed by Ryan (Fred Kelsey) into the kitchen. Again police are surprised at his resemblance to Ralph.
Paul tries to question Evans and then the lieutenant about the murders and is told they can make no headway. Kessler takes a phone call telling him to come to the coroners office.
While speaking with the coroner (Robert Strange) Mrs. Mason comes in and asks to see the body. She is left alone while the coroner returns to talk with Kessler. They hear a scream and return to the morgue where Mrs. Mason says he moved. Kessler tries to get Jules to say who tried to kill him, but when he sees Kessler he dies of fright before he can say anything.
As they discuss what happened, Evans begins serving dinner, explaining that the new cook is having trouble getting started. In the kitchen the new cook remarks how she hopes she can do a good job. Evans asks her if she has read the papers to which she says no.
After dinner a game of chess is played by Kessler and Paul, who wins. Evans calls Kessler, explaining that the cook wants to quit. He agrees to speak to her. Paul and Virginia go upstairs to their rooms. Kessler convinces the cook to stay on.
Returning to review his chess moves, he is drawn to the window where his wife peers in as the rain pours down. Meanwhile Virginia retires to bed. Kessler, in a trance starts to go back toward the kitchen as lightning strikes. This seems to alter his plan. He goes upstairs and goes to Pauls door. Hesitating, Paul hears someone at the door and goes to listen. Kessler redirects to his daughters room and prepares to kill her. When lightning strikes again he is awakened from his trance and leaves her room. As he goes downstairs, Paul follows him into the library. Staring out the window, Paul asks if he is all right. Although somewhat confused, he tells Paul that he is all right and needs nothing. Paul leaves for his room and Kessler sits to read. Again he is drawn to the window where his wifes face puts him into a trance. He reaches out to the window but she is gone.
The next morning Paul, Virginia and Kessler come downstairs and notice that the portrait has been slashed. He wonders if anyone was hurt. In the kitchen he questions Evans who tells him the cook was going shopping that morning. Finding her room empty, they notice her coming in with groceries. Kessler tells her he is so happy to see her and leaves. She wonders why he said that and Evans tells her he was afraid shed been murdered.
The lieutenant enters the front door and is shown the torn portrait. He tells Kessler that no one entered the house since his men were staked out outside. Paul calls him into the library, pointing out feet visible under the curtains. When he pulls the curtain aside Ryan is shown to be dead.
After questioning the cook, who tells them food keeps disappearing, the lieutenant leaves the kitchen. Paul finds a fiber in the portrait and shows it to the lieutenant, who goes upstairs to try to match it. When he returns, Kessler identifies the robe as his. They are told it was found in Evans room. Paul cautions him to not jump to conclusions and suggests Evans be examined by a psychiatrist, who is called in.
Kessler asks his daughter to summon Evans and for her to go to her room. At this point the lights go out. Evans is seen carrying two lamps. He gives one to Virginia, who tells him he is wanted in Kesslers room. Entering, he is told to sit in Kesslers chair for some questioning. The psychiatrist (Lloyd Ingraham) begins by asking if Evans thinks Kessler is insane. Puzzled, he answers no.
In the kitchen, Mrs. Kessler enters and gets some food out of the refrigerator to eat. The police walk in and catch her. They take her to the lieutenant. On the way she notices the torn portrait, telling them she knows the woman in it who is mad and cant go home. She is humored by the officer and taken upstairs.
She is presented to the others as having been snooping around. She tells Kessler Im dead, Charles. Im dead. Im afraid to come home. Youd kill me. Youd kill anybody. Immediately he goes into a trance, which is noticed by the lieutenant. He tells them to remove the woman and they follow Kessler. He walks out into the hall, followed by the lieutenant and Paul. Suddenly he turns and attacks the lieutenant. Meanwhile Mrs. Kessler passes out in the other room and is declared dead. At that moment Kessler comes out of his trance and releases the lieutenant. Asking what happened, Kessler is told they have the murderer. He asks Evans? and is told no, its you, Mr. Kessler. He reacts with shock.
As they come downstairs, Kessler approaches the portrait and speaks: I knew youd come back. Nothing can part us now, my darling.