A poor Midwest family is forced off of their land. They travel to California, suffering the misfortunes of the homeless in the Great Depression.

Tom Joad: I been thinking about us, too, about our people living like pigs and good rich land layin' fallow. Or maybe one guy with a million acres and a hundred thousand farmers starvin'. And I been wonderin' if all our folks got together and yelled...
Ma Joad: Oh, Tommy, they'd drag you out and cut you down just like they done to Casy.
Tom Joad: They'd drag me anyways. Sooner or later they'd get me for one thing if not for another. Until then...
Ma Joad: Tommy, you're not aimin' to kill nobody.
Tom Joad: No, Ma, not that. That ain't it. It's just, well as long as I'm an outlaw anyways... maybe I can do somethin'... maybe I can just find out somethin', just scrounge around and maybe find out what it is that's wrong and see if they ain't somethin' that can be done about it. I ain't thought it out all clear, Ma. I can't. I don't know enough.
Ma Joad: How am I gonna know about ya, Tommy? Why they could kill ya and I'd never know. They could hurt ya. How am I gonna know?
Tom Joad: Well, maybe it's like Casy says. A fellow ain't got a soul of his own, just little piece of a big soul, the one big soul that belongs to everybody, then...
Ma Joad: Then what, Tom?
Tom Joad: Then it don't matter. I'll be all around in the dark - I'll be everywhere. Wherever you can look - wherever there's a fight, so hungry people can eat, I'll be there. Wherever there's a cop beatin' up a guy, I'll be there. I'll be in the way guys yell when they're mad. I'll be in the way kids laugh when they're hungry and they know supper's ready, and when the people are eatin' the stuff they raise and livin' in the houses they build - I'll be there, too.
Ma Joad: I don't understand it, Tom.
Tom Joad: Me, neither, Ma, but - just somethin' I been thinkin' about.
Casy: I wouldn't pray just for a old man that's dead, 'cause he's all right. If I was to pray, I'd pray for folks that's alive and don't know which way to turn.
[last lines]
Ma Joad: Rich fellas come up an' they die, an' their kids ain't no good an' they die out. But we keep a'comin'. We're the people that live. They can't wipe us out; they can't lick us. We'll go on forever, Pa, 'cause we're the people.
Tom Joad: Seems like the government's got more interest in a dead man than a live one.
Casy: Maybe there ain't no sin and there ain't no virtue, they's just what people does. Some things folks do is nice and some ain't so nice, and that's all any man's got a right to say.
Casy: Tom, you gotta learn like I'm learnin'. I don't know it right yet myself. That's why I can't ever be a preacher again. Preachers gotta know. I don't know. I gotta ask.
Ma Joad: Well, Pa, a woman can change better'n a man. A man lives sorta - well, in jerks. Baby's born or somebody dies, and that's a jerk. He gets a farm or loses it, and that's a jerk. With a woman, it's all in one flow, like a stream - little eddies and waterfalls - but the river, it goes right on. Woman looks at it thata way.
[the family is leaving the farm, heading for California]
Al Joad: Ain't you gonna look back, Ma? Give the ol' place a last look?
Ma Joad: We're going' to California, ain't we? All right then let's go to California.
Al Joad: That don't sound like you, Ma. You never was like that before.
Ma Joad: I never had my house pushed over before. Never had my family stuck out on the road. Never had to lose everything I had in life.
Tom Joad: That Casy. He might have been a preacher but he seen things clear. He was like a lantern. He helped me to see things clear.
Muley Graves: There ain't nobody gonna push me of my land! My grandpa took up this land 70 years ago, my pa was born here, we were all born on it. And some of of us was killed on it! ...and some of us died on it. That's what make it our'n, bein' born on it,...and workin' on it,...and and dying' on it! And not no piece of paper with the writin' on it!
Casy: You don' know what you're a-doin'.
Ma Joad: There, gramma! There's California.
Grandma Joad: Phbbtt!
Tom Joad: Takes no nerve to do something, ain't nothin' else you can do.
Tom Joad: If there was a law, they was workin' with maybe we could take it, but it ain't the law. They're workin' away our spirits, tryin' to make us cringe and crawl, takin' away our decency.
Grandpa Joad: It's my dirt! Eh-heh! No good, but it's - it's mine, all mine.
Tom Joad: What's the matter, Grandpa?
Grandpa Joad: What's the matter? There's nothin' the matter. I just - I just ain't goin', that's all.
Pa Joad: What you mean you ain't goin'? We got to go. We got no place to stay.
Grandpa Joad: I ain't talkin' about you. I'm - I'm talkin' about me! I give'r a good goin' over all last night, and I'm a-stayin'!
Pa Joad: But you can't do that, Grandpa! This here land's goin' under the tractor. We all got to get out.
Grandpa Joad: All except me, and I'm stayin'!
Tom Joad: What about Grandma?
Grandpa Joad: Take her with ya!
Ma Joad: There ain't no family now. And Winfield, what's he gonna be this way? Growin' up wild. And Ruthie too. Just like animals. Got nothing to trust.
Gasoline Attendant: You and me got sense. Them Okies got no sense and no feeling. They ain't human. Human being wouldn't live the way they do. Human being couldn't stand to be so miserable.
Grandpa Joad: I smell spare ribs. Somebody's been eatin' spare ribs. How come I ain't got none?
Uncle John: He is telling the truth... the truth for him.
Tom Joad: Sure don't look none too prosperous.