Roy Martin aka Roy Morgan is a burglar and former war-time Radio & Electronics Engineer who listens in to radio police calls, allowing him to stay one step ahead of the cops.

Johnny Mack goes to work on "Ma" Curtis' ranch, to the disapproval of his friends, rancher Glenn Hadley and his sister Beth, who are at odds with her. Secretly, Ma's foreman Stoner is plotting with real estate man Ed Dutton to ruin her ranch and acquire it cheaply, with controlling water rights. Johnny stops henchman Dade in an attempt to dynamite the barn and Stoner, supposedly taking him to the sheriff, kills him. Johnny stops Glenn and Beth from tearing down a Curtis fence in order to get their cattle to water, but Glenn refuses to help even after Johnny explains he is helping Ma in order to find out who is behind the attacks on both ranches. Ma pretends to fire Johnny for saving Glenn from an ambush. As the outlaws attempt to rustle Ma's remaining cattle, Johnny, Alibi and Glenn join forces.

Pursued by the big-time gambler he robbed, John Muller assumes a new identity—with unfortunate results.