Gemma is a thirty-two-year-old operatic soprano who travels to San Francisco for a fresh start. Orphaned at fourteen, she is wary of relying on others and places all her trust in her vocal talent. She suffers from debilitating migraines that threaten her career, but she possesses immense lung capacity and a fierce determination to succeed on the stage.

Suling is a twenty-year-old Chinese American seamstress living in San Francisco's Chinatown. Following the recent death of her parents, she faces pressure from her uncle to accept an unwanted arranged marriage. Resourceful and observant, she frequently dresses in men's clothing to safely move around the city outside Chinatown. She plans to achieve independence through her exceptional sewing and embroidery skills.

Alice is the curator of botany at the California Academy of Sciences. She is a practical, independent woman in her early fifties who ignores traditional gender expectations in favor of her scientific research. She is deeply observant of nature and actively encourages other women to pursue their vocations.

Reggie is a talented visual artist who challenges the social norms of the era by wearing men's clothing and living an unconventional lifestyle. As an artist, she faces unequal pay and relies on wealthy patrons to support her work. She shares a deep connection with Suling Feng but abruptly disappears, leaving Suling searching for answers.

Henry is a wealthy railroad tycoon and a prominent patron of the arts in San Francisco. Operating out of a lavish octagonal mansion on Nob Hill, he collects rare botanical specimens, Chinese artifacts, and talented artists. He presents himself as a charming benefactor who can guarantee artists' careers while hiding a dark obsession with control.

Nellie is a visual artist and former roommate of Gemma Garland during their time in New York. The two shared a close bond while struggling to make ends meet in the city. Nellie recently moved to San Francisco, prompting Gemma to follow her there, but Gemma is distressed to find that Nellie has inexplicably vanished from her boardinghouse room.

Madam Ning is the pragmatic proprietor of the Palace of Endless Joy, a brothel in Chinatown. She was the best friend of Suling's late mother and continues to act as a guardian figure for Suling. Ning runs her business as ethically as the profession allows, strictly protecting her workers and managing the city's corrupt power structures with sharp intelligence.

Sergeant Clarkson is a white police officer in San Francisco. In a city where law enforcement typically ignores or preys upon Chinatown's residents, Clarkson maintains a complex arrangement with Madam Ning. His presence ensures that the police do not harass her establishment.

Enrico Caruso is a world-renowned opera tenor performing with the Metropolitan Opera company during their San Francisco tour. He is passionate about music and respects true artistry over mere performance. He takes a professional interest in Gemma's singing abilities.

George is a local accompanist and vocal coach working in San Francisco. Having studied music in Buenos Aires, he brings a steady, calming presence to the chaotic environment of the opera company. He is hired to accompany Gemma during her daily practices and quickly becomes a supportive confidant.

Third Uncle is Suling's guardian who took over her family's laundry business following the death of her parents. Struggling with an opium addiction, he severely mismanages the business. He aggressively pressures Suling to enter an arranged marriage that will benefit him financially.

Old Kow is an elderly Chinese man who works as an assistant in the Feng family's laundry business. He operates a pushcart around San Francisco's steep hills, relying heavily on Suling to translate for him and manage the business's daily operations.

Dr. Ouyang is an older physician in Chinatown who frequently visited Suling's mother when she was alive. He is now the man that Third Uncle has chosen for Suling to marry, an arrangement that Suling deeply distrusts and seeks to escape.