Canadian Rod Cameron had been around Hollywood for several years, as a contract-player for Paramount and Universal, and had starred in two of Republic's best, action-packed serials---1943's "G-Men vs. The Black Dragon" and "Secret Service in Darkest Africa"---both of which he played a character named Rex Bennett, in the rare instance of Republic duplicating a hero character in one of their serials (aside from The Lone Ranger and variations of the Zorro character.) Universal, following the voluntary departure of Tex Ritter from their series-westerns---a mistake Ritter often said he regretted---then signed Rod Cameron to take over as the star of their B-western unit. Cameron starred in six films before he was elevated to bigger-budgeted and non-series films at Universal and, later, much grittier and more-acclaimed westerns at Republic and Allied Artists.
The first in the B-series, "Boss of Boomtown", was a western version of the "Quirt and Flagg" feuding-buddies-in-the-army films, with Steve Hazard (Rod Cameron) and Jim Ward (Tom Tyler)as Civil War cavalry sergeants constantly battling over girls, horses or anything that came up that had more than one side to it. On the day before their enlistment is up, a stagecoach is held up and robbed of the mine payroll. Among the passengers are Norman Brett (Robert Barron), Dale Starr (Vivian Austin) and Blain Cornwall (Sam Flint.) MIss Star has inherited the Emporium gambling palace from an uncle; Brett is a prominent mine owner, and Cornwall ostensibly is an assayer, but is, in reality a Treasury Departmen agent. Later, Jim, Steve and their pal "Chatter" Bob (Fuzzy Knight) get into trouble, Steve talks Jim in re-enlisting, but fails to do so himself, as does "Chatter." Jim is not a happy trooper at this turn of events.
Cornwall enlists Steve to help him in his investigation and has Steve hold up a stagecoach, to enable him to join the bandit gang, which is headed by Brett, and abetted by Sam Ridgeway (Jack Ingram), who runs the Emporium for Dale.
Jim, not knowing the reason for Steve's activities, trails him and he and Sergeant Dunne (Max Wagner) arrest Steve and "Chatter" and return them to Fort Rocky for jailing. This puts a crimp into Steve's plan to stop the holdup of the Army pay wagon by Brett and Ridgeway's gang.