Felps decides to plant lettuce on his property. But rancher Cass Casey's herds regularly ransack Felps' grounds... Furious, he hires Lucky Luke for protection from Casey. Felps wants to surround his property with barbed wire, which in the Old West is regarded as a provocation. And so, war is declared between the ranchers and the farmers... Lucky Luke will need all his skills as a mediator to reconcile everybody!