Colonel Ferris, a wealthy farmer in northern California, is strongly opposed to hydraulic mining, a new method developed during the gold rush of the 1870's, which is flooding the area's prosperous farmlands. Despite Ferris' political stance, Jared Whitney, a mining engineer from the East, becomes friends with the colonel's son Lance and falls in love with his daughter Serena. Family tensions deepen when the colonel's brother Ralph gives up farming to go to San Francisco to work for his wife Rosanna's father, Harrison McCooey, a leader in the mining venture. When Lance follows Ralph, the colonel, focusing his anger on Jared, forbids him to see Serena. Jared is called to San Francisco by McCooey, and although Jared is opposed to a plan to build a new dam to increase water power, he stands behind the company. When Serena learns that her father has been confiscating Jared's letters, she too goes to San Francisco, where Rosanna throws a lavish party, during which it announced that the farmers are taking legal action against the miners. Now Serena and Jared find themselves on opposite sides. The courts support the farmers, but McCooey's gang use mine foreman Slug Minton to keep the mines in operation. In a desperate attempt to stop the pumps, Lance is killed, and Jared finally understands McCooey's greedy nature. Ready to fight, the colonel leads a group of farmers to battle at the mine site, but it is Jared who wins the victory by blowing up the controversial dam. The court upholds its decision in favor of the farmers, and Jared and Serena are reconciled.