Viktor is a brilliant Jewish nuclear physicist working on theoretical physics during the Soviet evacuation. He is prone to insecurity but deeply devoted to the pure pursuit of scientific truth. His life is shaken when he receives a smuggled letter from his mother in a Ukrainian ghetto, awakening his consciousness of his Jewish identity. He faces intense moral and professional pressures from the Soviet state regarding his research.

Lyudmila is Viktor's wife and the eldest daughter of the Shaposhnikov family. She is consumed by anxiety for her son Tolya, who is fighting at the front as a young artillery officer. Her intense maternal focus isolates her from her husband and other family members. She retreats into her own private suffering, judging those around her for not understanding her pain.

Lyudmila's younger sister is an independent and sharp-witted woman who bristles at the suffocating dogmatism of the Communist Party. Separated from her husband, she seeks a more personal, free existence and works to secure basic living permits in a hostile bureaucratic system. She wrestles with the complex emotional ties of her past and her growing feelings for a new lover.

Krymov is an Old Bolshevik and military commissar whose entire identity is fused with the Party. He is stern, dogmatic, and a veteran of the Revolution who believes absolutely in the historical necessity of the state's actions. His ideological rigidity complicates his personal life and leaves him vulnerable as the political tides of the war shift unpredictably.

Novikov is a competent, pragmatic, and highly capable tank corps colonel leading forces in the massive Soviet counter-offensive. Unlike the Old Bolsheviks, he is not an ideologue but a practical soldier whose authority stems from genuine military skill. He hopes to survive the war and build a simple, peaceful life.

Mostovskoy is an Old Bolshevik who has been captured and placed in a German concentration camp. He attempts to organize an underground resistance among the prisoners while holding fast to his revolutionary ideals. However, his steadfast ideology is tested by the horrific environment and his fellow prisoners.

Sofya is a secular, assimilated Jewish army doctor who is captured and herded onto a train. In the brutal, dehumanizing conditions of the transport, she reconnects with her Jewish identity. She finds profound meaning in protecting those weaker than herself, ultimately redefining her purpose in the darkest of places.

The matriarch of the Shaposhnikov family, Alexandra represents the moral and intellectual legacy of the pre-revolutionary Russian intelligentsia. She is a compassionate woman who prioritizes individual kindness over rigid ideology, serving as a quiet emotional anchor for her sprawling family during a time of immense national trauma.

Getmanov is the political commissar of Novikov's tank corps. He is a quintessential Party apparatchik—shrewd, cynical, and deeply attuned to the nuances of power. He uses ideology as a practical tool to advance his career, showing a chilling ability to balance personal tenderness with professional ruthlessness.

The charismatic, fiercely independent commander of House 6/1. He operates his perilous outpost like an egalitarian micro-society, viewing the war as a fight for personal freedom rather than a vehicle for state ideology. His insubordination and dark humor infuriate the political officers sent to control him.

A former Tolstoyan and prisoner in the German camp who is viewed by some as a "holy fool." Having witnessed massive state-sponsored atrocities, he writes a manuscript rejecting grand ideological systems in favor of small, private acts of "senseless kindness." He believes all state systems inevitably lead to violence.

Viktor Shtrum's mother, a Jewish doctor who was unable to evacuate before the German invasion. She is forced into a ghetto, where she endures the horrific reality of the Holocaust while penning a deeply moving testament of love to her son.

A quiet, orphaned six-year-old Jewish boy who is herded onto a train bound for a concentration camp. Traumatized by the violence he has witnessed, he retreats into childhood memories and fears until he is taken under the wing of a compassionate stranger.

The director of the Stalingrad power station and Lyudmila's brother-in-law. A widower, he clings to his post amid heavy shelling while desperately trying to ensure the safety of his pregnant daughter. He faces immense pressure to maintain the station's output despite catastrophic damage.

Stepan Spiridonov's pregnant daughter. She stubbornly refuses to leave the perilous ruins of Stalingrad, pining for the young fighter pilot she fell in love with while he was wounded. She insists on facing the war on her own terms.

A young fighter pilot in reserve who is deeply in love with Vera. He reflects on his memories of her while preparing to fly perilous combat missions over the burning city of Stalingrad.

An SS Obersturmbannführer who engages his Soviet prisoners in disorienting philosophical debates. He coldly argues that National Socialism and Stalinist Communism are ideological mirror images, using philosophy as a method of psychological torture.

Viktor Shtrum's scientific mentor and the director of the institute. He represents pure intellectual integrity, prioritizing scientific truth over the state's narrow, practical demands, which inevitably puts him at odds with political authorities.

Viktor's collaborator and colleague in Kazan. He is deeply fearful of the state's political paranoia due to past traumas. He slowly distances himself from Viktor when the political winds shift against his friend.

Sokolov's wife, who offers a quiet, calming presence to Viktor amidst his professional and personal turmoil. She shares a deep, unspoken emotional connection with the physicist that complicates all of their lives.

A young female radio operator assigned to the perilous House 6/1. She manages the tense, informal atmosphere of the bunker and develops a tender connection with a young soldier, finding brief moments of humanity amid the constant danger.

A youngster fighting in House 6/1 who idolizes Commander Grekov. He finds a sense of true family among the defenders of the ruined building and falls deeply in love with the radio operator Katya.

Lyudmila's son from a previous marriage and Viktor's stepson. He serves as an artillery officer at the front, and his wartime fate becomes a source of consuming anxiety and ultimate devastation for his mother.

Viktor and Lyudmila's teenage daughter. She clashes with her father over politics and begins a romance with a soldier, navigating her youth in the shadow of her family's grief and the overarching trauma of the war.