A wealthy wallflower suspects her penniless playboy husband of murder.

Johnnie Aysgarth, a charming scoundrel, prevails upon his female admirers to introduce him to Lina McLaidlaw, the prim, spinsterish daughter of wealthy General McLaidlaw. Under the pretense of escorting Lina to church, Johnnie takes her for a walk along the hillside, where he affectionately names her "monkeyface" and questions her severe appearance. When Lina returns home and overhears her parents discussing their matronly daughter, Lina impulsively kisses Johnnie and agrees to meet him later that afternoon. Although General McLaidlaw warns his daughter that Johnnie is not to be trusted, and despite the fact that he breaks their date, Lina anxiously awaits word from him. One week passes, and on the night of the Hunt Club Ball, Lina receives a telegram from Johnnie, asking her to meet him at the ball. Johnnie crashes the party and invites Lina for a ride. In the car, Lina, who has transformed herself into a beauty for the ball, blurts out her love for Johnnie, and when he admits that he is falling in love with her, she invites him to her house for a drink. There, Johnnie proposes to Lina in front of her father's portrait, and when he taps the painting, it falls from the wall. The next morning, Johnnie and Lina elope. Upon returning from their honeymoon, the newlyweds take up residence in an extravagantly furnished house that Johnnie has rented. When Lina learns that her husband is penniless and had planned to live on her income, she protests that her small allowance is not enough to support them and insists that he find a job. To placate his bride, Johnnie accepts an offer to work for his cousin, Captain George Melbeck. Their married life is blissful until one day, Gordon Cochran "Beaky" Thwaite, a friend of Johnnie's, comes to visit and tells Lina that he saw her husband at the racetrack that day. When Lina notices that the museum quality chairs, a wedding gift from her father, are missing, Beaky suggests that Johnnie sold them to cover his gambling debts. Johnnie makes up a story about the disappearance of the chairs, but when Lina sees them for sale in the window of a village antique shop, she knows that Beaky was right. Soon after Lina's discovery, Johnnie returns home, bearing expensive gifts that he claims he bought with his winnings from the track. Lina is angry when Johnnie admits to selling the chairs to bet on the horses, but forgives him when the chairs are returned to their home. Beaky, Lina and Johnnie then toast Johnnie's good luck. The toast proves almost fatal to Beaky, who suffers an allergic reaction to his brandy, and Johnnie warns him that the drink will be the death of him. While in town one day, Lina impulsively goes to visit Johnnie at his office and discovers that he has been fired for embezzling £2,000, the exact amount of his race track winnings. Returning home, Lina begins to pack her suitcases when she realizes that she loves Johnnie too much to leave him. As Lina tears up her farewell note, Johnnie enters the room with a telegram notifying her of her father's sudden death. When Lina's only bequest from her father is his portrait, Johnnie asks if she regrets marrying him. After reaffiriming her love for him, Lina tells Johnnie that she knows he has been fired. When she pretends not to know the cause, Johnnie tells her that he did not get along with Melbeck and informs her that he now plans to go into land development. Johnnie then convinces his bumbling friend Beaky to invest in his company. Lina voices her concern about Beaky, and Johnnie menacingly warns her to stay out of his business affairs. The next evening, Johnnie informs Lina that he has decided to call off the deal, but insists upon showing Beaky the land first. When she awakens the next morning, Johnnie and Beaky have already gone, and Lina, who has envisioned Johnnie pushing his friend from a cliff, speeds off to find them. Relieved when she discovers the cliffs are deserted, Lina returns home to find Beaky and Johnnie in the living room. After announcing his plans to travel to Paris and dissolve the corporation, Beaky invites Johnnie to accompany him, and Johnnie agrees to drive as far as London. Several days later, the police arrive to question Lina about Beaky's death in Paris. Learning that Beaky died by gulping a snifter of brandy in response to a challenge by his English companion, Lina becomes alarmed and calls Johnnie at his club in London. Her panic is intensified when she discovers that Johnnie checked out of his hotel the previous day. Soon after, Johnnie returns home and becomes angry when he learns that Lina informed the police about his business dealings with Beaky. The next day, Lina visits her neighbor, Isobel Sedbusk, a writer of murder mysteries, and discovers that Johnnie borrowed a mystery detailing the use of brandy as a murder weapon. Returning home, Lina finds the book hidden in Johnnie's desk drawer, along with a letter promising the repayment of the money he embezzled. When the insurance company calls to inform Johnnie that they have answered his recent inquiry by letter, Lina sneaks a look at Johnnie's mail and discovers that he has inquired about borrowing money on her life insurance policy. When the company notes that the benefits are payable only at the time of death, Lina begins to fear for her life. At dinner that night, Johnnie questions Isobel and her brother Bertram, a coroner, about an undetectable poison. Later, when Lina is unable to sleep, Johnnie brings her a glass of milk. Certain that the milk is lethal, Lina leaves it untouched and announces that she is going to stay with her mother for a few days. Insisting upon driving her to her mother's house, Johnnie recklessly speeds along the cliffside curves. When Lina's car door swings open, Johnnie reaches to grab her arm, but she pulls away from him. Johnnie then stops the car, and when Lina runs out, screaming, he denounces her for pulling away from him when he tried to save her and declares that she will never have to see him again. Johnnie's words make Lina suspect that his interest in poison was for his own suicide, and he admits that because he was unable to repay his debt, he did consider suicide, but has now decided that prison is the more honorable solution. When he explains that he left London to visit the insurance company in Liverpool to inquire about borrowing money on her policy, Lina apologizes for doubting him and begs for another chance. Johnnie then turns the car around, and they drive home, to begin their marriage again.