Stefania is a Catholic teenager from a farming family who moves to the city of Przemyśl to work. She operates the Diamants' shop and quickly becomes close to the Jewish family. Fiercely independent and resourceful, she uses her quick wit to survive in Nazi-occupied Poland. She refuses to stand by while the people she cares about face persecution.

Helena is Stefania's six-year-old sister. She endures physical abuse and abandonment at a farmhouse before Stefania rescues her and brings her to Przemyśl. Despite her young age, Helena learns to follow strict rules and keep life-or-death secrets, acting as a vital partner in her older sister's risky endeavors.

Max is one of the Diamant brothers. He experiences the severe brutality of forced labor and the ghetto but refuses to accept confinement. Possessing a strong will to survive, he takes massive physical risks to escape his circumstances. He relies on Stefania for assistance and utilizes his practical skills to engineer hiding places.

Mrs. Diamant is a Jewish matriarch who runs a shop in Przemyśl. She treats Stefania with consistent kindness, quickly integrating the Catholic teenager into her family. She dispenses valuable life lessons about avoiding cruelty and prioritizing humanity during difficult times.

Izio is the second oldest son in the Diamant family. He flirts with Stefania and forms a romantic bond with her before the war begins. As the political situation deteriorates, he worries about the future and asks Stefania to wait for him when he is forced to go away.

Mr. Diamant is the patriarch of the Diamant family. He observes religious traditions, such as fasting for Yom Kippur, and attempts to protect his family as their rights and property are systematically stripped away.

Emilika is a Catholic woman in her early twenties who works at a photography studio. She befriends Stefania after the other residents leave the apartment building. She helps Stefania by taking photographs for forged documents and devising cover stories, though she refuses to directly hide Jewish citizens herself.

Henek is a brother in the Diamant family. He works in a labor camp and maintains a strong relationship with his girlfriend, Danuta. He struggles to adapt to the constant danger and sometimes stubbornly insists on returning to the ghetto despite the evident risks.

Danuta is a young Jewish woman dating Henek. She recognizes the extreme danger of the ghetto and takes independent action to secure her own survival, running away from Henek and clashing with his decisions.

Chaim is a brother in the Diamant family and a dedicated medical professional. He tries to heal starving people in the ghetto hospital despite lacking food and basic medicine.

Markus Berdecki is a Polish policeman. He catches Stefania breaking the law but chooses not to arrest her, instead using his authority to pursue her romantically. He invites her to his home and leverages his knowledge of her secrets to demand physical affection.

Lubek is a young man who works alongside Stefania at the screw factory. He frequently helps her meet her daily quota of thirty thousand screws. He expresses jealousy toward other men in her life and becomes hostile when he believes she is associating with an SS officer.

Dr. Schillinger is a Jewish dentist forced into the ghetto. He relies on Stefania's network for survival and demonstrates quick thinking when confronted by authorities, pretending to be Stefania's angry boss to deflect suspicion.

Dziusia is a young Jewish girl who must cross heavily guarded areas to escape the ghetto. She displays significant courage when moving through the city's dangerous checkpoints to reach safety.

Hirsch is an older Jewish man trying to survive the liquidation of the ghetto. He possesses a pragmatic understanding of the city's criminal element but compromises the safety of his group by sharing sensitive information about their hiding place.

Siunek is Hirsch's grown son. He coordinates with Max to secure a hiding place and helps manage the daily logistical challenges of living in secret.

Malwina Bessermann is a young Jewish mother. Desperate to save her children from the ghetto, she uses a threatening note to force Stefania to provide shelter. Her demands for specific foods and threats to call the Gestapo create intense anxiety for the other concealed individuals.

Cesia is Malwina's fifteen-year-old daughter. She takes on a parental role during her mother's illness, working to keep her calm and prevent her from exposing their hiding place.

Janek is Malwina's ten-year-old son. He assists his older sister in managing their mother's emotional outbursts.

Karin is a young German nurse working at the newly opened hospital across the street from Stefania. Installed in Stefania's apartment by military order, she treats her host as a domestic servant. She slaps Helena over a minor infraction but later sends an apology through another nurse.

Ilse is a German nurse who moves into the apartment alongside Karin. She complains about the lack of modern plumbing and electricity in Stefania's home. She freely consumes Stefania's food and brings soldiers into the apartment, drastically increasing the danger for everyone hidden inside.

Mrs. Krajewska is the overseer of Stefania's new building. She acts as a strict but sometimes helpful presence, forcing Stefania and Helena to create elaborate cover stories to explain their activities and food consumption.

Mrs. Krawiecka is a wealthy Polish woman who lives in a large home. She falls for Stefania's forged photograph of an SS boyfriend but later coordinates efforts to save Jewish citizens. She provides Stefania with heavy sacks of food to support her household.

Dorlich is a Jewish mailman. He utilizes his position to facilitate communication and movement before requiring a hiding place himself.

Januka is a friendly coworker at the Minerway factory. She supports Stefania during long shifts and shares terrifying rumors about the consequences of hiding Jewish people.