One of the last bills signed by President Lincoln authorizes pushing the Union Pacific Railroad across the wilderness to California. But financial opportunist Asa Barrows hopes to profit from obstructing it. Chief troubleshooter Jeff Butler has his hands full fighting Barrows' agent, gambler Sid Campeau; Campeau's partner Dick Allen is Jeff's war buddy and rival suitor for engineer's daughter Molly Monahan. Who will survive the effort to push the railroad through at any cost?

The Rangers in New Mexico are being disbanded but Bob Houston gets them to make one more ride. They go after the outlaw gang led by Hashknife. They catch Hashknife, but he escapes taking Barbara with him and Bob and Slim have to go after him again.

Judith Endicott, the daughter of a wealthy eastern banker, vamps Philip Randolph, an Arizonan, when he comes east to talk business with her father. Philip proposes and discovers that Judith has only been kidding him along. He returns angrily to Arizona, and the elder Endicott, accompanied by his daughter, follows him west. With her father's permission, Richard "kidnaps" Judith and takes her to a deserted Indian cliff dwelling, where she must cook and care for him. Bert Durland, Judith's fiancé, follows after her, and his Indian guide steals all of the horses. Judith and Bert and Philip start back to civilization across the desert, and Bert goes berserk from the heat. They are rescued by cowboys, and Judith returns east, "kidnaping" Philip and taking him with her.