Hopalong Cassidy meets Belle Starr in this rather somber entry in the long-running Western series. Belle (Natalie Moorhead) is being released after serving a five-year prison sentence for standing by her outlaw husband, Sam. The sheriff (John Beach) wants to drop her off in a Nogales dancehall (read: brothel), but Hoppy (William Boyd) forces him to let her go back to her ranch. Meanwhile, back at the Bar 20, all is not well. Ranch hand Twister (Leo McMahon) is conspiring with Belle's foreman, Dan Ringo (Alden Chase), to rustle the Bar 20 cattle and Lucky (Russell Hayden) is blamed. Wounded in the resulting melee, Lucky is cared for by Belle and her daughter, Jacqueline (Dorothy Short), while Hoppy and Windy (George "Gabby" Hayes) investigate the goings-on. Trimmer Windler (Lane Chandler) is suspected to be behind the rustlings, but there is no proof and the slippery villain is free to conspire with Ringo to steal Belle's herd. Hoppy's trap to catch the rustlers backfires when the sheriff is murdered. Soon he, Belle, and Jacqueline find themselves outnumbered by the gang. While Ringo promises to let the women go unharmed if Hoppy surrenders, a fearless Belle, her guns blazing, goes up against him alone and is mortally wounded.