Song is a fierce, independent migrant worker who sacrifices everything to support her son's musical talent. After a devastating separation at a train station, she turns to the food delivery gig economy to survive and fund her relentless search. She is deeply driven by her memories of her late husband and her determination to provide River a better life.

An 11-year-old piano prodigy with a chronic lung condition, River possesses perfect pitch and a sensitive nature. After losing his mother in the crush of the Beijing Railway Station, he relies on his musical abilities to survive in a terrifying new city. He eventually finds himself caught between his working-class roots and the wealthy, insulated environment of his new guardian.

A highly regarded piano teacher in Harbin who takes River on as a free student. While he provides crucial technical training, his intense personal ambition and volatile methods create a toxic environment, leading him to make dangerous decisions to ensure his student's competitive success.

An elegant, wealthy, and reclusive former concert pianist. After discovering River living secretly in the train station, she takes him into her luxurious compound, offering to rebuild his technique from the ground up while insulating him from the hardships of the city.

Song's late husband is a kind and supportive construction worker whose memory acts as a moral center for his family. He carved two clothespin dolls before leaving for a job in Shenyang, providing a lasting symbol of family unity before his tragic death in an on-site accident.

A boisterous, cheerful food delivery worker who approaches his hazardous job with a reckless glee. He helps Song find her footing in the gig economy app, secures her a room in a courtyard house, and offers a vital source of community and emotional support.

A wealthy, confident young pianist from Beijing who studies under a renowned teacher. She becomes a vital link to the normal teenage world for River, understanding the intense pressures of classical music while challenging his attempts to hide his past.

A practical, stern woman living in rural Lakeyard. She represents a survival-focused worldview, advocating for harsh economic realities over sentimentality, which frequently puts her at odds with her daughter's fierce devotion to River.

A kind, middle-aged night janitor at the train station. He provides immediate refuge for River by allowing him to sleep in a converted supply closet and sharing his food while the boy hides from danger.

Phyllis's husband, who lives with dementia in their upscale Chaoyang Park compound. He forms a gentle, confused bond with River, mistaking the boy for a childhood friend named Little Red.

A beautician who lives alongside other migrant workers in Beijing. She becomes part of Song's reliable found family, supporting her through the challenges of city life.

Jade's boyfriend and a resident of the shared Beijing courtyard. He joins the communal effort to support his neighbors in their daily struggles.

A food delivery worker who shares the warren of rooms in the Beijing courtyard house. He represents the camaraderie of the invisible gig economy workforce.

A highly esteemed piano teacher in Beijing. Song views him as the ultimate mentor who can unlock her son's potential, driving her decision to relocate to the capital.

The housekeeper employed by Phyllis and Eight. She helps maintain their pristine, luxurious lifestyle, providing a sharp contrast to the gritty world outside.