In Dubious Battle deals with a fruit-workers' strike in a California valley and the attempts of labor unions to organize, lead, and provide for the striking pickers.
Jim Nolan meets Harry Nilson who initiates Jim's application process to become the newest member of the Party. 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.
Momentum for strike action builds after old Dan breaks two rungs out of a ladder and falls. 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.
The course of the strike is recounted in some detail, including the politics of the local growers, the support by Al through his little luncheonette, the "sweet-talking" of some locals in order to garner food and other help for the pickers, and personal crises and tragedies in individual cases. Mac emerges as a heroic but quite single-minded figure; Jim's occasional doubts are presented as well.
Jim joins Sam in a picket as they go after some 'scabs' in the apple orchard. Sam's pickets violently injure them. While out on the road Dakin, the leader of the pickers, is ambushed by a vigilante group at gunpoint. Later, the Anderson barn is burned down by vigilantes. In the aftermath, Jim is killed by a high powered shotgun. As the book ends, Mac is continuing to rouse and motivate the picketers, in spite of seemingly hopeless odds.
