Set in the 1890s, the story centers around the life of a Sicily family, the Collogeros, living in California and working in the winemaker business, and their confrontation with a powerful railroad and land baron named William Bradford Berrigan (Hopper), who is after their lands and the ones that belong to the other families in the area. Berrigan's plan is to get control of the properties in order to build a new railroad. When the conflict escalates, he murders the patriarch of the family, Sebastian Collogero (Giannini), and in response, his son Marco (Roberts) claims for justice. With the help of his family and others, Marco starts an open guerrilla war against Berrigan.