Context

Tom Joad is paroled from the State Penitentiary after serving four years for manslaughter having killed a man in self-defense.

He returns to Oklahoma in the midst of the Depression to find the land and crops wasted by a prolonged drought.

He meets Jim Casy, a former preacher at Tom’s church when he was a child. Casy explains that he no longer has the calling to be a preacher, although he still believes in the Holy Spirit, which for him is love.  He maintains that all people are holy, everyone being a small part of the whole soul, which is mankind.  Tom and Casy walk back to the Joad’s farm. 

They find it abandoned having been ‘tractored’ by the bank, which was standard practice when land was repossessed.

They meet one of Joad’s neighbors Muley Graves who tells them that the family has moved to their Uncle John’s home and they are preparing to leave for California to find work.

The next day Tom and Casy arrive at Uncle John’s to find the family busy packing their belongings in preparation for the long trek to California. Casy asks if he can travel with them, and they agree. They sell their valued possessions for a meager return of funds, but this is needed in order to purchase food for the journey.

All are keen to make the journey and leave the Oklahoma Dustbowl, apart from Grampa who wants to stay and live off the land. The family finds it necessary to spike Grampa’s coffee in order to get him onto the truck. The roads out of Oklahoma are full of migrant farmers seeking a new life in the West.

They come across the Wilson family whose car has broken down and they offer to help. The Wilson’s say that Grampa can use their tent, as he has not fully recovered from the drug he had been given. Grampa has a stroke and dies.

Tom and his brother Al fix the Wilson’s car and the two families set off together.

However, their car breaks down again and the families are forced to stop.  Granma’s health deteriorates and Tom suggests that they should split up, but Ma refuses to allow this.  She is becoming the foundation of the whole family.

They approach the desert bordering California and Sairy Wilson is ill with cancer as well and is unable to continue. 

The Joad’s make their own way across the California desert at night, but Ma knows that Granma will not survive much longer. They cannot stop in the desert even although Granma has died and when they eventually climb out of the desert May tells the family that Granma is dead.  The family has no money to bury her properly and they leave her body with the coroner.

The Joad’s stop at the first camp they come to which is poorly run and squalid comprising of tents and makeshift shelters. 

One of the young men from the camp, Floyd Knowles, is trying to obtain a contract in writing concerning the wage they have been offered to pick crops. The police are called in who accuse Floyd of being a troublemaker. Tom trips up one of the cops and Casy kicks him. Casy takes the blame for the argument as Tom is still on parole.  Casy is arrested.

The Joad’s travel on and eventually arrive at a Government-run camp where the community governs itself electing committees and taking responsibility for sanitation, discipline and entertainment. For a few weeks the Joad’s are comfortable, but they are still not able to find regular work and they must move on again.

They hear that there is work, picking peaches in Tulare. When they arrive there is much unrest in the town and there is a large group of men shouting and waving at the newcomers.  At the camp they are told that they will be paid 5 cents a box if the whole family works. This is barely sufficient to feed the whole family. After the first day’s picking, Tom wanders out of the camp and meets up with Jim Casy.  Jim advised Tom that the owners only want to pay 2 ' cents a box and that he is leading a strike against the landowners. Tom is annoyed to learn that he is in fact strikebreaking.  The police surprise the group of men and without provocation Casy is hit on the head and killed.  Tom retaliates by killing the policeman who had killed Jim.  Tom manages to escape, but he receives a broken nose for his trouble and has to hide to avoid detection.

Tom has become a fugitive until his scarred face and broken nose heal.

The Joad’s decide to flee the peach ranch and they manage to find work, picking cotton and they share a boxcar with the Wainwright family. Tom hides in a nearby cave and Ma brings him food on a regular basis.

One day, Ruthie, Tom’s younger sister becomes involved in a fight with another child and she lets it slip that her big brother is hiding because he has killed two men.

Ma warns Tom who leaves for his own safety with a plan to carry on the work that Jim Casy had begun.

Al gets engaged to Agnes Wainwright and the two families have a brief celebration.

Heavy rains descend on the area making it impossible to pick cotton and the water levels start to rise.  The men try to build a dam to stop the water flooding the boxcar and Rose of Sharon, another sister of Tom goes into labor and gives birth to a stillborn child.

The Joad’s abandon the boxcar in favor of higher ground and they find an old barn already occupied by a young boy and his starving father.  The father has not eaten is six days and is unable to keep down solid food.

Rose of Sharon offers him the breast milk no longer needed for her own child. The others leave as she cradles the dying man to her breast.