In Europe and the United States at the turn of the twentieth century, young women started working in record numbers. Many women from working-class backgrounds had gained enough education to enter white-collar professions, which helped to bolster a burgeoning lower-middle class. The narrator of Henry James's novella is one such woman. She works in the telegraph "cage" in Cocker's grocery store. There, she observes—but does not partake in—the activities of upper-middle class and elite Londoners:

The barrier that divided the little post-and-telegraph-office from the grocery was a frail structure of wood and wire; but the social, the professional separation was a gulf that fortune, by a stroke quite remarkable, had spared her the necessity of contributing at all publicly to bridge.

While earning a living and having her own independent life provides a certain satisfaction, the telegraphist understands that her employment is a temporary respite from her future life of marriage and children. The job itself is rather boring, but the lives of the clients for whom she sends telegrams—and the content of the wires themselves—are fascinating.

Her current prospect is to marry Mr. Mudge, a dull but devoted suitor of her own class (who is also a former colleague who has gotten promoted). She is far from optimistic about this marriage, as she already knows everything there is to know about her fiancé:

During the three months of his happy survival at Cocker’s after her consent to their engagement she had often asked herself what it was marriage would be able to add to a familiarity that seemed already to have scraped the platter so clean.

There is (as is often the case in Henry James's novels) a big "however" in this scenario. The boring job and the vision of her dull future are just not enough for "our young friend," as James calls her—who has a vivid imagination.

She expends her imaginative powers by envisioning herself within her clients' lives. In particular, she takes a fancy to a charming young man who begins to frequent the "cage." Having recently returned from Paris, he is constantly sending telegrams to a woman, Lady Bracknell, who also uses the service. The protagonist begins to see him every day and know him by his signatures: Philip or Everard.

Understanding that he is of a different stratum, she notes that he carries himself with an ease that he takes for granted, a class privilege so ingrained that he seems unconscious of it:

[H]is high pleasantness, his relighting of cigarettes while he waited, his unconscious bestowal of opportunities, of boons, of blessings, were all a part of his splendid security, the instinct that told him there was nothing such an existence as his could ever lose by. He was somehow all at once very bright and very grave, very young and immensely complete; and whatever he was at any moment it was always as much as all the rest the mere bloom of his beatitude.

She becomes fascinated—even obsessed—with him, and deludes herself that she has a romantic future with him.

James takes the reader through the various plot complications that finally reveal that this young man is not actually of an exalted stratum but a fortune-hunter. His employment in the shop outside the "cage" is, in many ways, as tedious a job as hers is inside, as his success in life also depends on a good match. He never even suspects that she has a romantic interest in him.