After breaking free from a chain gang, the prisoners seek refuge in the desert 

Zach Provo saw the dawn of the twentieth century from inside the walls of Yuma's prison. After twenty-eight years on an Arizona chain gang, Provo seizes an opportunity to escape. He smashes one guard's face with a rock, takes his shotgun, and blows the other guard away. Soon the twenty-eight men of the chain gang are on the loose. Provo sends most of them into the desert to hide, holding back the nine smartest fugitives. While the police hunt for the men who ran, his group waits for nightfall, hidden in the mud of a dry riverbed. At dark they sneak back into Yuma. Escape was only the first part of Zach Provo's plan. Now comes time to deal with the man who sent him away--and the bloody vengeance of which he has dreamed for decades.