Roy Rogers, a Nevada State Ranger Captain in charge of the Rangers Reclamation Service, makes a trip to Las Vegas for the annual Heldorado Frontier Days Festival, as he wants to help his old friend Gabby Whittaker who originated the idea (at least, in this film).In Las Vegas, Roy meets heiress Carol Randall, who has been selected as the Queen of the Heldorado. Roy is informed that the F.B.I. wants an immediate investigation of the counterfeit thousand dollar bills that are being passed over the gambling tables at the casino.

In Roy Rogers' Down Dakota Way, the deadly hoof-and-mouth disease has struck the herd owned by evil rancher H. T. McKenzie (Roy Barcroft). To avoid an expensive quarantine on his stock, McKenzie plans to murder the local veterinarian (Emmet Vogan) before the latter can report his findings to the government. Rogers manages to straighten out the situation by appealing to the sensibilities of the aunt (Elizabeth Risdon) of McKenzie's hotheaded hired assassin (Byron Barr). The film also bears several musical numbers from Roy, Dale Evans, and Foy Willing and the Riders of the Purple Sage.

Gridley is mining silver from an old Mexican mine and bringing it into the USA thru a passage into his worthless mine. Border guard Rogers suspects Gridley and finally finds the secret entrance to the Mexican mine. He sends Lee Madison for help only to have her captured by Gridley. Trigger brings help that takes care of Gridley's men and now Roy has to rescue Madison.

Peter Potter Jr. returns to claim his father's gold, which is nowhere to be found.

In the grand tradition of Disney's great musical classics, Melody Time features seven timeless stories, each enhanced with high-spirited music and unforgettable characters. You'll be sure to tap your toes and clap your hands in this witty feast for the eyes and ears.