Grusha walks across the glacier for another seven days until she reaches her brother's house. Her brother Lavrenti greets her. When he realizes that she has a baby, he asks her if there is a father. She tells him no, and he asks her not to tell his wife Aniko that there is no father, explaining that his wife is "religious." Aniko tries to come up with several excuses for why Grusha cannot stay with them, saying that the countryside is too boring for city folk or hinting that Grusha might have scarlet fever or tuberculosis (consumption). Lavrenti persuades her to allow Grusha to stay.
Grusha remains with her brother through most the winter months. As spring approaches, she tells Michael that they must be "small as cockroaches" so that Aniko will let them remain until it is springtime. Lavrenti enters her room and asks Grusha if it is too cold. She hastily pretends that it is warm enough for her. In his desperation to get her out of his house, Lavrenti informs Grusha that must marry a dying man from the other side of the mountain. That way she leaves the house and Michael is made a "legitimate" child since he will then have a father.
She protests, but Lavrenti explains that "you don't need a man in bed - you need a man on paper." Since the man is dying, Grusha finally agrees to marry him so that she can become a widow. She crosses the mountain and meets with the man's mother. Lavrenti has agreed to pay the woman 400 piasters to arrange the marriage. When the woman discovers that Grusha has a child, she demands more money. Lavrenti agrees to pay an additional 200 piasters in order to ensure that Grusha can live on the farm for at least two years after her future husband dies.
A drunk monk arrives and performs the ceremony. The dying man does not even move, but his mother says "yes" to the marriage for him. As soon as the marriage is over, the monk asks the mother if she wants him to perform Extreme Unction, a sacrament for anointing the dead. The mother refuses, saying that the wedding already cost enough.
The peasants that have arrived to watch the wedding and eat the reception food comment on Jussup's condition. They indicate that everyone originally thought that Jussup was only faking his sickness in order to avoid getting drafted into the war. However, now that it appears that Jussup is about to die, they regret having felt that way. While all the guest continue to talk and eat the food, Jussup suddenly sits up and then sinks back into the bed again. Suddenly all the guests start talking about the latest news which has just arrived. It turns out that the Grand Duke has gathered together a new army and is returning to fight with the princes that rebelled against him the previous year.
When one of the guests remarks that the war is over and that the army can no longer draft anyone, Jussup suddenly sits upright in bed. Jussup then gets out of bed and throws out all the guests. After several weeks Jussup demands that Grusha start to have sex with him, that she perform her "wifely duty." She reluctantly agrees. Many months pass and Grusha starts to slowly forget about her promise to Simon.
One day she is washing linen by the stream. Michael is with her and he goes to play a game with some children. They reenact the beheading of the Governor, Michael's father. However, instead of playing the part of the Governor like the other children want him to, Michael insists that he be allowed to behead the fat boy, who represents the Fat Prince.
Grusha laughs at the children playing, but when she looks up she sees Simon. He has returned to marry her. She sadly informs him that she is now married and she tries to explain that Michael is not her real child. He first demands that she give him the silver cross back, but she refuses. Simon then waits while two Ironshirts grab Michael. The soldiers ask Grusha is Michael is her child. Grusha is forced to say that Michael is in fact her child. As soon as she makes this claim, Simon leaves her. The Ironshirts state that the child actually belongs to Natella, the Governor's wife, and they take Michael with them. Grusha follows them back to the city where the her case is given to Azdak, the city judge.
Throughout this act Brecht makes fun of religion again. Jussup is meant to represent Joseph who married Mary when she was already pregnant. The depiction of him as a draft dodger is actually quite comical when performed onstage. Lavrenti's wife Aniko is constantly described as religious, even to the extent that she uses "religion" as an excuse for kicking Grusha out of her home. The final parody of religion is presented in the form of a drunk monk. The monk who performs the wedding ceremony is a "cheap monk" who does not do a very good job.
Three more sacraments are presented in this act, those of marriage, holy orders, and extreme unction. All occur when the monk is present. He himself represents Holy Orders, or at least a parody of Holy Orders. He then performs the marriage ceremony and immediately thereafter, he asks the mother if she would like him to perform extreme unction, a sacrament in which the dead are anointed. She refuses, claiming that the wedding cost too much already.
Grusha now completes her development in the plot by going through the last four steps. The seventh step is when she gets denies to Lavrenti that she is cold. This allows her to stay in her brother's house for a while longer. Eight is when she gets married, thus breaking her promise to Simon. Nine is when she agrees to have sex with Jussup, thereby losing her virginity. Ten is when she is confronted by the Ironshirts and must choose between claiming Michael as her child and losing Simon or disclaiming Michael and getting Simon. She chooses Michael, thereby sacrificing Simon. At this point she has given away everything that she has to give in order to keep Michael.
The children's game is important because it not only makes a mockery of the adult world, but it also foreshadows the death of the Fat Prince. Michael is initially asked to play his father and allow the older boys to behead him. Instead he chooses to behead the Fat Prince, indicating that there will be soon be a change in the regime. It is important to realize that the children are foreshadowing only the action in the play; in terms of sequential action the Fat Prince has already been beheaded since the Grand Duke returned to power several months earlier during Grusha's wedding.