Lucia Harper is left on her own when her husband is away on business. She decamps from Balboa Island and heads for Los Angeles to confront Ted Darby, a smooth-talking but unscrupulous criminal, and insists he end his relationship with her 17-year-old daughter, Bea Harper. Darby agrees to break things off, but only if Lucia pays him. She argues that his insistence on money has cheapened the situation, saying that when she tells Bea “how deeply you feel about her,” the girl will choose to end things with him on her own terms.
Back home, Bea confronts her mother with disbelief; Darby’s call had already reached Bea, who refuses to accept that money changed anything. Lucia forbids Bea from seeing Darby, but that evening Bea slips out to the family boathouse to meet him anyway. Darby hints that money could smooth things over and that their relationship might still continue, which repulses Bea. A struggle ensues, Bea strikes him, and he collapses. Unseen, Darby tries to pursue her but loses his balance and falls, dying in the water.
The next morning, Lucia discovers Bea anxious and sheltering her fear, and Bea finally reveals what happened. Lucia goes to the boathouse, but there is no sign of Darby. By morning light, Darby’s body turns up near a jetty. Lucia, shaken, uses a motorboat to dispose of the evidence in a swamp, and a murder investigation swiftly follows.
Into this fraught situation arrives another L.A. criminal, Martin Donnelly, the partner of a brutal loan shark, Nagel. Donnelly now holds Bea’s letters to Darby as leverage. Nagel has been grooming this debt as a shield, and Lucia must raise the full sum of $5,000 to keep Bea’s relationship from becoming public knowledge.
As Lucia scrambles to secure funds, Donnelly develops a growing attraction to her. He tells her he has refused his “cut” and, if she can assemble half the money, he might be able to mollify Nagel—or even settle the matter himself. Lucia pawns jewelry and scavenges what she can, but she only amasses about $800. When she meets Martin Donnelly to hand over the money, he assures her that she is in the clear: a suspect has been arrested in connection with Darby’s death. Guilt gnaws at Lucia; she tries to convince Donnelly that she is the killer, but he dismisses her, arguing that even if the man in custody is innocent of that crime, he is “guilty of a hundred other things” and the family must come first.
Things shift when the suspect is released. Nagel waits in the boathouse and presses for payment in full. Donnelly arrives and attacks Nagel; in the ensuing struggle, Donnelly is wounded but ultimately strangles Nagel to death.
Donnelly then confides a warm, dangerous sentiment to Lucia. She plans to notify the authorities and end the arrangement, but he asks for a drink first. While she steps away, Donnelly drives off in Nagel’s car with the letters, intending to disappear. Lucia chases him, and a desperate pursuit ensues. In the car, Donnelly rifles through Nagel’s pockets for Bea’s letters, loses control, crashes through a fence, and collides with a tree, trapping himself beneath the wreckage.
Lucia finds him and hears his plea to not help him, believing it safer for the law to find him this way. He hands over the letters and dies there, leaving Lucia to confront the aftermath. Back at home, her two children return from an evening out. Her son mentions hearing about “a terrible accident,” and Bea shares that the police reported the dying man had admitted to killing Darby just before the car collision. The revelation lingers, leaving Lucia to face the tangled consequences of a night that spiraled from desperate choices to a fatal confrontation.
