Johnson, the owner of fertile Western acres, secures exclusive control of the water supply by constructing a large dam and refuses to allow his neighbors irrigation privileges. The owners of adjoining lands make vehement protest, but to no avail, and Johnson becomes known as “the Water Hog.” Grace Lewis purchases the ranch next to Johnson’s land, and arriving on the scene, she finds that the arid tract is practically valueless because of the Water Hog’s high-handed control. She, too, makes a protest, but can accomplish nothing. The spirited girl determines to show Johnson that he has gone too far. Under the cover of darkness, she directs a party of men who destroy the dam. They hide on a hill nearby, and, heavily armed, prepare to thwart the efforts of Johnson’s men to reconstruct the dam, which has caused all of the trouble. But Johnson is not to be dealt with so easily. He declares he will fight to a finish, and, securing arms for his men, he endeavors to drive Grace’s party from the hill. When things are going against Grace, Ralph, Johnson’s son, who has recently returned from college, climbs up the hill to overpower his father’s enemy. To his amazement he finds a girl with whom he has already fallen in love, and he hears Grace’s side of the story. As a result, he prepares a paper for his father to sign, which forces Johnson to discontinue his interference with the neighbors. Johnson is not inclined to give up the fight, but Ralph’s statement that he will tell the whole ranch how one girl held off the Johnson party, enables the young man to carry his point.