The series tells about the fate of the Russian intelligentsia on the eve, during and after the revolutionary events of 1917. In the center of the story is the life story of the two sisters of the Bulavins, Darya and Katerina, and their beloved: officer Vadim Roshchin and engineer of the Baltic Telegin factory.

Set in 1914, sisters Katya and Dasha navigate love and betrayal amid the changing spirit of St. Petersburg. Dasha studies law, becomes entangled with poet Bessonov, and meets engineer Telegin. Katya admits her infidelity to her husband and leaves for France. As war breaks out, Dasha works in a hospital and learns that Telegin has gone missing.

Bessonov has recovered at Hannah's farmhouse, where Hannah is alone following the death of her son and her husband. Bessonov writes a poem for Hannah, but she confesses that she cannot read. He reads the poem to her, and they share an emotional embrace. An armed soldier enters the house and sees them. It is Hannah's husband, very much alive. In St. Petersburg Vadim and Katya are married. Dasha is very pregnant and waits for Telegin, who is working. Impatiently, she decides to go out and walk to meet him. The temperature is freezing and the streets are dangerous and her impulsiveness leads to tragedy.

As the war deepens, Dasha aids her friend Liza, who serves on a hospital train. Telegin endures captivity, escapes, and reunites with Liza in a military hospital, but his heart remains with Dasha. Katya reconciles with her husband but falls in love with soldier Roshchin. After recovering, Telegin heads back to Petersburg in search of Dasha.

Spring 1917. The Tsar abdicates and revolution sweeps through Russia. Dasha marries Telegin, while Katya learns that her husband Nikolai has died. Katya weds Roshchin, but Dasha loses her baby and, devastated, blames Telegin and leaves him as he returns to the front.

As revolution reshapes the country, Dasha and Telegin marry, and Katya loses her husband. She later marries Roshchin, while tragedy strikes Dasha, whose baby dies during childbirth. Overwhelmed by grief, she separates from Telegin, who goes back to war.

1918. Dasha returns to work in a hospital as Telegin fights for the Red Army and is wounded. Roshchin joins the police in Samara but soon breaks with the revolutionaries. In Petrograd, Dasha loses her job after being denounced and, struggling to survive, agrees to work secretly against the Bolsheviks.

As civil war rages, Dasha works in a hospital while Telegin fights on the Red side. Roshchin and Katya grow disillusioned with the revolution, and Dasha, dismissed from her job and left hungry, is drawn into anti-Soviet underground activities.

Krasilnikov rescues Katya from Makhno’s men and hides her on a farm. Telegin and Roshchin cross paths as soldiers on opposite sides of the war. Dasha begins working with Savinkov’s anti-Bolshevik network and receives a mission to assassinate Lenin, but at the rally, she cannot pull the trigger.

Katya escapes from captivity, while Roshchin and Telegin’s fates intertwine in the chaos of the civil war. Dasha joins Savinkov’s conspirators, is ordered to kill Lenin, but fails to carry out the assassination.

Savinkov needs Dasha alive to recover stolen jewels. Dasha flees Moscow with a decoy bag, while Katya escapes from Krasilnikov, who kills her pursuers. Telegin, Roshchin, and Sapožkov all meet again amid the fighting and are arrested, but a bombing allows them to escape as the church holding them collapses.

Katya is rescued from captivity; Telegin and Roshchin’s paths cross again amid war and chaos. Dasha joins Savinkov’s underground and is tasked with assassinating Lenin but cannot bring herself to do it, leading her deeper into the revolutionary turmoil.