Undine is a young woman from Apex City who relocates to New York with the singular goal of conquering elite society. She relies on her striking appearance and persuasive charms to secure wealthy connections. Lacking an understanding of financial realities, she expects constant luxury and becomes frustrated when her expectations are unmet. She possesses a restless energy, always searching for a grander lifestyle than the one she currently occupies.

Ralph is a gentleman from the established Dagonet family who prefers writing poetry to pursuing business ventures. He believes he can elevate Undine away from her superficial crowd by showing her the quiet dignity of old-money culture. His traditional upbringing leaves him unprepared for the aggressive financial demands of modern marriage, forcing him into a stressful corporate career.

Elmer is a self-made businessman from Apex City who operates as a private secretary for Harmon Driscoll. He possesses a hidden past involving Undine, giving him leverage over her family as they try to establish themselves in New York. He aggressively plays the stock market, representing the ruthless, modern pursuit of capital over old-money prestige.

Raymond is a French aristocrat who meets Undine during her time in Europe. As the heir to a noble title, he treats wealth as a community resource meant to maintain family estates and historical artifacts. He approaches life with a deep reverence for tradition and family obligation, clashing with modern American sensibilities.

Peter is a superficial but incredibly wealthy member of the New York elite. He enjoys flirting with Undine and offers her glimpses of the opulent lifestyle she desperately wants. He uses his vast resources to fund his own amusements, frequently traveling to Europe to avoid taking serious responsibility for his actions.

Undine's father, who made his fortune in Apex City before moving to New York. He continuously works to finance his daughter's escalating social demands. The financial pressure of city living and speculative business deals severely strains his resources and health.

Undine's mother, a quiet woman who struggles to adapt to New York society. She defers entirely to her daughter's ambitions and worries constantly about the family's social standing and past secrets.

Peter's wife and a former romantic interest of Ralph Marvell. She comes from established old money and provides Ralph with a sympathetic ear when he faces personal and financial difficulties.

The young son of Undine and Ralph. He spends much of his early life managed by nurses or visiting relatives, as his mother frequently views him as an inconvenience to her social calendar.

Ralph Marvell's sister and a respected member of New York society. She extends one of the first formal dinner invitations to Undine, acting as a bridge between the Spragg family and the established Dagonet circle.

A society manicurist who acts as a connector for wealthy women. She carries a bag full of newspaper clippings detailing the lives of the elite, feeding Undine's obsession with high society.

An acquaintance of Undine who initially attempts to help her enter New York society. Undine later views Mabel as a social liability and actively tries to distance herself from her.

A popular portrait artist who caters to the New York elite. He paints Undine's portrait, contributing to her rising visibility in society.

A sociologist and friend of Ralph Marvell. He frequently observes the shifting dynamics between old New York families and newly wealthy individuals, offering commentary on social customs.

A prominent figure in European royal circles. She strikes up an acquaintance with Undine during her travels, offering Undine a pathway into exclusive foreign society.

Raymond de Chelles's aunt and an established figure in French society. She advises Undine on the rigid cultural expectations of the European aristocracy.

Ralph Marvell's grandfather and the patriarch of the historic Dagonet family. He represents the fading era of old New York prestige and traditional gentlemanly conduct.

A powerful and wealthy businessman. He employs Elmer Moffatt as his private secretary and spearheads massive corporate investments, representing the new wave of American capitalism.

Mabel's husband. He fails to meet his wife's evolving social expectations, leading to marital strain as she seeks greater prominence in New York.

A young woman from Apex City who successfully maneuvers her way into a wealthy marriage. She frequently intersects with Undine in Paris, serving as a reminder of their shared Midwest origins.

Raymond de Chelles's brother. His financial debts require the family to arrange a strategic marriage to an American heiress to secure funds and preserve their ancestral estates.