Napoleon sends General Savary to the Tsar to tell him how much his support of Austria wounds him, but also to learn Marshal Kutuzov's next move. Nikolai is reunited with Boris at his lodging, where they discuss the types of military career they seek. Prince Andre Bolkonsky arrives while Nikolai is relating his experiences at Schongraben. Nikolai is offensive to him about the worth of staff officers as they see no fighting. Savary reports back to Napoleon about the atmosphere of excitement at the Russian camp over what they see as their duty to half French ambitions. Kutuzov's army is camped on the Pratzen Heights and Napoleon hopes they can be drawn down to avoid attacking them there....

Twenty thousand men have died at Austerlitz and Marshal Kutuzov has written to Prince Bolkonsky to inform him that Andrei is among them. Maria is afraid to pass on this news to Andrei's wife, Lisa, as her pregnancy is at an advanced stage. There is a happier mood at the Rostovs when Nikolai arrives home bringing Denisov with him. While Natasha is no longer infatuated with Boris, Sonya is still in love with Nikolai, but wants him to be free if that is his wish. Pierre, now married to Helene, is just about the only man in Moscow who is unaware that his wife has taken a man called Dolohov as her lover. Dolohov is introduced to the Rostov family; he feels that it is high time he was married and immediately shows an interest in Sonya....

Pierre learns that Dolohov is Helene's lover and, at a banquet hosted by Count Rostov in Kutuzov's honor, he is deliberately provoked by his rival. When Dolohov announces aloud that after the banquet he has a date with a rich pretty married woman, Pierre finally loses control and challenges him to a duel. The duel takes place the next day and Pierre seriously wounds Dolohov. After Helene learns what has happened she asks Pierre for a separation, telling him that being his wife has been an embarrassment to her. Denisov, who has had his eye on Natasha, proposes marriage. She like Denisov but does not wish to marry him. A chance meeting at a post-house leads a desolate Pierre to a new way of life. Meanwhile at Tilsit, Napoleon and the Tsar prepare to sign a truce....

Marshal Berthier tries to persuade a reluctant Napoleon that they should leave Moscow and return to France, while Marshal Davout believes that they should sit out the winter there. Napoleon himself wishes to march on Kutuzov and his army in Kalouga but is forced to order a retreat. The Russian prisoners, who include Pierre and Karatayev, are forced to march with the retreating French army, pushing their carts along through the snow. Any prisoners who are unable to walk any further or are too sick to carry on are shot dead. Karatayev becomes unwell and Pierre feats that he will not survive. The retreat is observed by Denisov and Dolohov who intend to attack the French once they have learned how many there are and how they are defended. Petya arrives and begs Denisov that he be allowed to join the attacking party....

Russia, 1820. Natasha and her children are staying with Nikolai and Maria at Bald Hills while Pierre is away. Nikolai falls asleep and thinks back to the year after the burning of Moscow, when the Rostovs were living in reduced circumstances in the city. Maria Bolkonskya came to visit them and Nikolai's pride prevented him from being polite to her. Countess Rostova insisted he return the courtesy by calling on her. When he did so, he reluctantly revealed to Maria that he had nothing to offer her and that was the reason why he felt he couldn't marry her. Nikolai wakes to find Maria, who is now his wife, and their son at his side. The pair discuss buying back the Rostov home at Otradnoe....