In the depths of the Great Depression, drought and mechanization strip the Joad family of their Oklahoma tenant farm, forcing them onto Route 66 with thousands of other displaced families chasing the promise of work in California's orchards. What they find instead is a state flooded with desperate migrants, land owned by a handful of banks and growers, and wages driven to nothing by the sheer number of families as hungry as they are.
Steinbeck follows the Joads — Tom, freshly out on parole; Ma, who becomes the family's true center of gravity; the preacher Jim Casy, wrestling his way toward a new kind of faith — through roadside camps, strikebreaking violence, and the slow erosion of everything they own, interspersing their story with broader interchapters that widen the lens to the whole migrant exodus.
Published in 1939 and awarded the Pulitzer Prize, The Grapes of Wrath is Steinbeck's angriest and most political novel, an indictment of unregulated capitalism's human cost and an argument, embodied in Ma Joad's endurance, for solidarity among the dispossessed as the only real defense against it.