It's been ten years since stage robber, Black Bart, has been paroled, but no one's seen hide or hair of the masked outlaw who once robbed hundreds of coaches with an unloaded rifle. Now a new string of hold-ups point to Bart - only this time the gun is loaded and at least one victim is dead. Crash, Dusty, and Alibi, are hired by the stage company to investigate the stick-ups, only to suspect that a local gambler could be the man behind the mask.
Cowboy star Ray "Crash" Corrigan's ranch in Susana Pass, California served as the principle location for Wrangler's Roost, the seventh in Monogram's popular Range Busters adventure series (1940-43). Corrigan entered pictures in 1934 as a stunt man before starring in the serials Undersea Kingdom and Darkest Africa (both 1936). Before the Range Busters, Corrigan appeared with fellow Range Buster, Max Terhune, in Republic's popular Three Mesquiteers western series.