First, readers are introduced to Mrs. Mooney, who is described as "a determined woman" who married an employee of her father's (he was a butcher). Once her father died, however, her husband began to drink, steal, and accrue debt, ruining the business. One night, he attacks Mrs. Mooney with a meat cleaver, and she leaves him, taking their two children, and opens a boardinghouse for lodgers and tourists. She makes decent money running the house, though her son, Jack, turns into a bit of a "hard case": he swears a lot and stays out late. He knows how to fight and always has a new "good thing" on which to bet.

Polly, Mrs. Mooney's daughter, sings songs about being a "naughty girl" to please the boarders (who are all men), and Mrs. Mooney's "intention was to give her the run of the young men." In other words, mother and daughter are sort of tacitly investigating which young man might be suitable marriage material. Polly eventually grows to care for a Mr. Doran, and, "At last, when [Mrs. Mooney] judged it to be the right moment, [she] intervened." She has a conversation with Polly, eager not "to seem to have connived," while Polly herself is made awkward by having to make "allusions of that kind." It seems, then, that Polly is pregnant. Mrs. Mooney decides to call Mr. Doran to a meeting and demand that he marry her daughter.

About halfway through the story, the narrative shifts from a focus on Mrs. Mooney's and Polly's thoughts to a focus on Mr. Doran's thoughts. He is made anxious by Mrs. Mooney's demands that he come down to speak with her. He has confessed the affair to his priest, gravely aware of the magnitude of his sin, and he fears that, should his boss learn of his behavior, "All his long years of service [would be] gone for nothing!" He knows he needs to marry Polly to make things right, but he sees that she's a "little vulgar" and worries his friends and family will think she is beneath him. Polly enters his room while he is thinking, and she declares that she will "put an end to herself" in her desperation.

He recalls the night of their first tryst: she tapped on his door to relight her candle (which had gone out just then), fresh from her bath and pleasantly, and purposely, perfumed. We realize, though Mr. Doran may not, that this was not an accidental meeting. He remembers how she has always tries to take care of him, their lingering kisses on the stair, and though he does not want to marry her, he sees that he must do so. As he descends the stairs to speak to Mrs. Mooney, he passes Jack, who addresses him coldly, and he remembers Jack's threats to anyone who behaves or speaks dishonorably to his sister: another reason to marry her. Polly waits upstairs, "cheerfully, without alarm," because she seems to know what will happen below and what the outcome will be. In the end, her mother calls her, and we are given to assume that Mr. Doran will, indeed, propose marriage, as Mrs. Mooney has planned all along.