In some happy valley somewhere in the west, cattle ranchers live and work contentedly on their own spreads, respecting their neighbors, helping and being helped, having occasional squaredances, until some rich guy from back east moves in and starts buying ranchers out. He knows that the railroad is about to come through, or gold is about to be discovered, making all the land much more valuable than it has been.
When they won't sell, he threatens them and intimidates their hired hands. When that doesn't work, a gang of masked marauders drives off their cattle, poisons their water, burns their buildings, and generally commits other mischief until, one by one, they begin to give in.
Finally, a single rancher remains. Often it's a pretty widow or the beautiful daughter of a murdered pioneer protecting what her family built. She is under tremendous pressure from the would-be land baron and his hot-headed, violent son who incompetently tries to kidnap or rape her or shoots a harmless old man or something equally heinous.