The central figure of the story is an activist attempting to organize abused laborers in order to gain fair wages and working conditions.

Mac "Doc" McLeod, the Party organizer, tells Jim they will go to the Torgas Valley (a composite location) in an attempt to rouse the two thousand fruit pickers against the Growers' Association, and to encourage the strike to spill over into the cotton fields in Tandale.

London becomes chairman of a committee of seven men, while Mac convinces Al Anderson's father to loan five acres as a base for the fruit pickers in exchange for them picking his crop for free.

Doc Burton is hired by Mac to maintain the sanitation of the strikers' camp, so as to prevent it from being disbanded by the Red Cross.

On publication, New York Times reviewer Fred T. March compared it to the "genial gusto" of the "picaresque" Tortilla Flat.

Steinbeck, he said, "is supremely interested in what happens to men's minds and hearts when they function, not as responsible, self-governing individuals, but as members of a group....

He said that "Steinbeck's bionomic interest is visible in all that he has done, from Tortilla Flat, in the middle Thirties, through his semi-biological Sea of Cortez, to his latest communiqués as a war correspondent in England."

In 1958, critic Alfred Kazin referred to In Dubious Battle and The Grapes of Wrath as "his most powerful books," contrasting them with Cannery Row and The Wayward Bus.

[6] The film stars Nat Wolff in the lead role, along with Josh Hutcherson, Bryan Cranston, Robert Duvall, Ed Harris, Selena Gomez, and others.