At Bald Hills, Andrei tells his father that he plans to marry Natasha Rostova. Prince Bolkonsky is not enthusiastic about the match and suggest that Andrei postpones the marriage for a year, saying that he will give his consent after that time, if Andrei still feels the same. A delighted Natasha agrees to marry Andrei despite the imposition of a year's wait. Pierre and Helene are now living in separate suites. She has become one of Petersburg's most popular hostesses, while he has tired of freemasonry and is consumed by thoughts of Natasha. When Nikolai arrives home on leave he finds that his family are in bad financial straits, to the extent that they may have to sell their home in Moscow. The Countess strongly hints to Nikolai that he may want to consider marrying an heiress....

Julia Karagina, who is now married to Boris Drubetskoy, pays a visit to the Rostovs and they discuss the prospect of leaving Moscow. Petya has joined a Cossack regiment but in line with the wishes of the Countess, Pierre transfers him to his own regiment which is training near Moscow. Pierre is unable to decide whether he should leave for Petersburg or stay in Moscow. Andrei meets Marshal Kutuzov again and tells him that his father is dead. Kutuzov believes that the forthcoming battle at Borodino will be pointless, as all that will change is that each side will lose some twenty thousand men. He also believes that the loss of Moscow is not important. Pierre meets up with Andrei at an encampment, but the battle begins before he has left the area....

The battle of Borodino is over, neither side having the energy to fight on. The loss of life has been as considerable as Kutuzov predicted. Pierre makes his way back to Moscow where he hears a proclamation stating that Moscow will be defended after all. Summoned to see Rostopchin, he learns that the speech was made in order to stem civilian panic and that the Governor is getting ready to leave. Rostopchin advises Pierre to leave the city, but he decides to remain in order to confront Napoleon, believing that their destinies are somehow inextricably linked - a view which he had derived from an interpretation of Revelation. Meanwhile, at the Rostov household, everyone is packing, when Natasha observes a seemingly endless line of Russian soldiers streaming out of the city....