A Russian émigrée who serves as a moral center in the narrative, marked by her commitment to practical acts of care despite her own poverty. She demonstrates the potential for human connection and moral attention through her interactions with others.

A skilled third-generation railwayman, whose role as an engine driver illustrates how systemic pressures can lead to disaster. His relationship with stoker Victor Garnier highlights themes of partnership and the human cost of industrial demands.

Younger and smaller than Guillaume, Victor is a stoker whose labor highlights the economic pressures placed on railway employees. His close working and emotional relationship with Guillaume underscores the collaborative nature of their roles.

A Black American painter in Paris, whose careful navigation of class and race informs his interactions. His internal struggles with inherited trauma and the constant social scrutiny he faces illuminate the pervasive impact of racism.

A young physiologist and daughter of a Cuban-born politician, marked by her scientific ambition and awareness of racial and gender biases. Her encounter with others demonstrates the complexities of medical authority and social boundaries.

A curious seven-and-a-half-year-old boy traveling alone, whose fresh perspective often challenges adult assumptions. His observations question the artificial systems and time manipulations of railway life.

A senior guard demonstrating unwavering commitment to railway standards, whose responsibilities include managing documentation and passenger safety. His faith in the system highlights the physical demands and unintended vulnerabilities of industrial work.