A band of Mexicans find their U. S. land claims denied and all the records destroyed in a courthouse fire. Their leader, Louis Chama, encourages them to use force to regain their land. A wealthy landowner wanting the same decides to hire a gang of killers with Joe Kidd to track Chama.
After the Civil War, a former Union colonel searches for the two traitors whose perfidy led to the loss of a close friend.
An accidental nerve gas leak by the military kills not only a rancher's livestock, but also his son. When he tries to hold the military accountable for their actions, he runs up against a wall of silence.
