Chapter 27
Cotton needed to be harvested and there were eager people ready to do the job. The payment was decent and they had experience picking cotton in their hometown. They purchased a container to gather the cotton and used the earnings from their first day's work to pay for it. The task was exhausting and laborious, as they had to carry and fill the heavy bag. Even the children assisted in filling it, while they conversed and sang while working.

The weight of the bag increased, and their payment was based on its weight. The employer accused them of adding rocks to it, but they denied it and claimed that the scale was faulty. Both sides were occasionally correct.

Despite the challenging nature of the job, it paid well and provided food. However, there was an influx of workers, causing the fields to be harvested quickly. Additionally, winter was approaching, and there would be no work available during that time.

Chapter 28
Since the Joads were among the first to arrive at the cotton field, they were able to secure one-half of a boxcar to live in instead of a tent. This afforded them the opportunity to purchase new clothing and enjoy a daily meat diet using the money they earned. However, while Ma was buying some Cracker Jacks as a special treat for Ruthie and Winfield, Ruthie got into an altercation with another girl over them. In her anger, Ruthie threatened the girl by revealing that Tom had killed two men and was hiding nearby.

Upon discovering the situation, Ma promptly visits Tom and he brings her to the cave where he has been concealing himself. Ma instructs him to depart and inquires about his plans. Tom responds that while he was in hiding, he had ample time for contemplation. He had been pondering on Casy's notion that all individuals are components of a single, vast soul, and that a single person's contribution to this soul was insufficient unless the entire soul was complete.

Tom believes that he has a responsibility to complete the task that Casy had initiated, and therefore, he intends to rally the people together. When Ma reminds Tom that Casy has been killed, he retorts that he will be more agile and quick-witted than Casy. When Ma expresses her concern about Tom's safety, he assures her that she will encounter his presence in any location where people require assistance or are engaged in a struggle for a more fulfilling existence.

While Ma is returning to the boxcar, she meets a man who is seeking people to work on his small 20-acre cotton farm the next day. He explains his issues with The Association regarding wages.

When she arrives back, the Wainwrights, who share the boxcar, express their concerns about Al possibly impregnating their daughter, Aggie, and causing shame for their family. Ma offers to speak to Al about this. Later on, Pa admits to Ma that he feels useless and can only dwell on the home they left behind. He expresses feelings of hopelessness, saying "We got nothin' now" and "Seems like our life's over and done." However, Ma refuses to accept this and assures Pa that they will continue on.

Al announces to everyone that he and Aggie are planning to get married, and settle down in a town where he can work as an automobile mechanic. Both families rejoice and decide to gather and harvest cotton together. However, they arrive early, only to find many other workers have already picked the field clean before noon. On their return to the boxcar, heavy rainfall starts, and Rose of Sharon develops shivers.

Chapter 29
The mountains were covered with dark clouds which brought about rain that started gradually and then became heavier. As a result, water accumulated in puddles, then ponds, and eventually in low-lying areas, forming lakes. The rivers and streams overflowed from their banks, causing flooding that destroyed the tent homes and cars. The people were forced to seek refuge on higher ground and felt hopeless due to the dire situation. Men and boys went out to look for food, even risking their lives by stealing and not even running away if shot at. The women observed the men closely, hoping for a sign of progress. However, they saw that fear was being replaced with anger, which meant that there was no chance of a resolution as long as this transition continued.

Chapter 30
Amidst the ongoing rains, Al shields the truck's motor. The Joads and Wainwrights, who have merged into a single family, contemplate departing, but since they are yet to be affected by the flooding and Rose of Sharon's health is deteriorating, Pa concludes that constructing a barrier to contain the floodwaters is the best course of action. As a result, he departs to request assistance from other men.

Upon his return, he discovers that Rose of Sharon is in the process of giving birth. He instructs the men to construct the embankment due to this circumstance. They work tirelessly throughout the night as the water level increases. They manage to successfully impede the water's flow until a tree gets uprooted and ruptures the bank, causing the entire area to flood. In a hurry, Al rushes to relocate the truck, but unfortunately, it fails to start, and he is forced to leave it behind in the deluge.

Rose of Sharon's child is born dead. Pa is questioning if there was anything he could have done to prevent it. When he leaves, Mrs. Wainwright arrives to give Ma a break. The two women discuss the importance of supporting one another and Ma reflects on how things have changed, explaining that in the past family always came first, but now anyone who is in need must be helped, especially when times are tough.

Pa, Al, and Uncle John check the water level to determine if it will cause flooding in the boxcar. To create a platform above the floor, they utilize a portion of the truck bed. Mrs. Wainwright requests that they bury the deceased child, despite it being prohibited by law. As they have no other options, Uncle John initiates the burial process, but eventually lets the body drift away in the stream.

Pa purchases bread and bacon with the remaining money for their breakfast. They gather together on the platform while the boxcar floor gets submerged in water. The following day, Pa brings ten potatoes which they consume, and spend another night.

The following day, Ma decides it is the right time to leave and instructs Al, who will remain with Aggie, to look after their possessions until they come back. While Pa carries Rose of Sharon, Uncle John carries Ruthie, and Ma carries Winfield, they make their way through the flood waters.

Ma observes a barn and assumes it's a dry place to stay, so she and the others decide to go there. Upon entering the barn, they come across dry hay and a young boy huddled over a man lying on his back. The boy explains to them that his father is extremely hungry and when he attempted to alleviate his hunger by stealing some bread, it made him sick and he vomited. The boy requests soup or milk for his father's nourishment.

Ma removes the wet clothes from Rose of Sharon and covers her with a dry blanket provided by the boy. She gazes at Rose with a look of inquiry, and Rose comprehends and signals her approval. Ma escorts the rest of the group out of the barn while Rose of Sharon places the head of the dying man onto her breast, which is filled with milk. 

“There!” she said. “There.” Her hand moved behind his head and supported it. Her fingers moved gently in his hair. She looked up and across the barn, and her lips came together and smiled mysteriously.