Rudi is a 17-year-old Jewish teenager from Slovakia who refuses to accept the subjugated identity forced upon him by the Nazi regime. Sharp and determined, he actively resists by attempting to flee to Great Britain to join the Allied forces. As his journey subjects him to capture and imprisonment, he transforms his goal from personal survival to bearing witness, using his prodigious memory to meticulously catalogue the atrocities he sees.

Gerta is a teenage girl from Slovakia whose fight for survival relies on psychological endurance and deception rather than physical escape. Forced to flee to Budapest, she assumes a false identity as a Catholic country girl, requiring constant vigilance to mask her accent and true background. She is incredibly resilient and intelligent, using her secretarial skills to eventually aid the resistance.

Filip is a young Jewish prisoner who is forced into the Sonderkommando, the unit tasked with the horrific job of working in the crematoria. Trapped in a position of unbearable complicity, he struggles with the futility of physical defiance. He resolves that his ultimate purpose must be to survive and bear witness to the unimaginable crimes he is forced to facilitate.

Fred is an older, more experienced prisoner from Rudi's hometown of Trnava. Pragmatic and composed, he utilizes his network and position within the camp to gather intelligence and coordinate survival strategies. His steady collaboration and practical mindset make him a critical ally in surviving the highly restrictive and deadly camp environment.

Heinrich Himmler is the Reichsführer of the SS and the chief architect of the Holocaust. Operating as a high-level manager of genocide, he embodies the cold, bureaucratic evil of the Nazi regime. He observes the systematic extermination process with total detachment, prioritizing efficiency, expansion, and extreme security over human life.

Rudolf Höss is the commandant of Auschwitz, responsible for implementing the logistics of the Nazi's mass murder campaign. He treats the extermination of human beings as a bureaucratic and logistical challenge, attempting to optimize the process to spare his SS guards emotional strain. He chillingly maintains a normal family life in a villa located just steps from the camp.

Ipi is an older Jewish prisoner and Filip's father. Assigned to the grueling Buna Command alongside Rudi, his physical strength rapidly fades under the horrific labor conditions. He clings to the false hope that his son is safe and playing in the camp orchestra, an illusion that provides him with vital emotional comfort during the torment.

Josef is a resilient teenager from Nováky who quickly bonds with Rudi upon their arrival at Auschwitz. Quick-thinking and resourceful, his ability to speak French proves to be a life-saving asset when navigating the brutal hierarchy of the camp's work details. He provides crucial mutual aid in an environment designed to pit prisoners against one another.

Max is Gerta's father, a former butcher shop owner whose life is upended by the fascist takeover of Slovakia. Forced to flee with his family, he struggles with the constant anxiety of living under forged papers in Budapest. The prolonged stress and subsequent detention weigh heavily on his spirit.

Jozefina is Gerta's mother, forced into a life of hiding and deception. She actively works to maintain their cover, sending her daughter on errands to practice speaking Hungarian. Despite her efforts to adapt, the relentless fear, interrogations, and torture gradually break down her resilience.

Franz is an Austrian kapo and a political prisoner who wears a red triangle on his uniform. While he projects brutality when SS guards are watching, he is privately somewhat humane and attempts to help the prisoners under his command by orchestrating small acts of sabotage to secure them extra food.

Richard Wiegleb is a vicious SS officer who manages the massive theft operation at Auschwitz. He frequently toys with and violently assaults the prisoners under his control, demanding absolute obedience and using extreme physical violence to maintain order and extract confessions.

Laco is a Jewish dentist who manages to survive in Auschwitz for several months before meeting Rudi. He possesses valuable knowledge about the camp's shifting labor structure and helps guide Rudi toward the comparatively safer Canada Command.

Marushka is a non-Jewish girl in Trnava who was once close friends with Gerta. As fascism takes root in Slovakia, she quickly adopts the state-sanctioned prejudice, revealing how the political climate provides moral justification for personal greed and betrayal.

Dmitri is a captured Soviet soldier imprisoned in Auschwitz. Hardened by his experiences, he provides Rudi with strict, pragmatic rules for attempting an escape, emphasizing the absolute necessity of trusting no one and moving invisibly.

Erwin is a childhood friend of Rudi who shares his desire for intellectual defiance against the state's restrictions. He is later deported to the Majdanek prison camp, where the brutal conditions render him emaciated and barely recognizable.

Josef is a teenager imprisoned in Nováky who boasts that his wealthy father can finance a journey to freedom. While he collaborates on the initial breakout, he ultimately proves unreliable when the reality of life on the run sets in.

Charles is a prisoner in Auschwitz who attempts to engineer a daring escape by trusting a driver he believes has a sympathetic background. His actions demonstrate both the intense desire for freedom within the camp and the fatal risks of placing trust in the wrong hands.

Martin is Gerta's boss in the Jewish underground resistance in Bratislava. He manages the office where Gerta secretly forges identity papers at night, representing the hidden networks of support operating in defiance of the fascist regime.

András is a boy in Budapest who provides Gerta with a brief, private romance. His presence offers her a fragile illusion of an ordinary teenage life while she lives in constant fear under a false identity.

Josef is an old friend of Gerta who has become an active member of the Jewish underground resistance. Recognizing her value, particularly her blue eyes and blond hair, he recruits her into the organization's dangerous work.