The Last Musketeer (1952)

Cattle buyer Rex Allen rides into Taskerville and sees two men toss Slim Pickens, a water diviner hired by the local ranchers, into a wagon. Rex chases the wagon to the barn of rancher Lem Shaver, where he learns from Slim that Russ Tasker, a wealthy rancher and owner of the only artesian-fed reservoir in the valley, has charged such high prices for water that the ranchers are bankrupt. Tasker's henchmen kill rancher Matt Becker and have his son Johnny branded as an outlaw. Rex learns that the Beckers had found a meager water supply and Rex suspects that is what led to the killing and the charges against Johnny. With the aid of Slim and Johnny's sweetheart, Sue, Rex finds that the Becker spring is fed from the same underground lake that feeds Tasker's well-guarded reservoir. But Rex is jailed for aiding Johnny.