The abusive young widow of an elderly mine owner conspires with thieves to conceal the fact that the deceased man's gentle teen-aged granddaughter may be the rightful heir to his estate.
Sgt. Preston travels to Goldport to discover the source of counterfeit currency. He goes undercover as a prospector and with Yukon King's help starts working on the case which puts his lady friend Sherry in danger.
When a greedy mining executive files an unwarranted lawsuit against the claim of two brothers, his debt-laden son convinces one of the brothers to assist him in robbing his father's gold shipment.
Released after 10 years in prison, psychopathic Carl Stack holds Sergeant Preston responsible for his incarceration and hires assassin Pierre La Fitte to murder him from ambush.
Sergeant Preston must work to clear King's reputation after a murderous claim-jumper falsely (and publicly) accuses the dog of causing a prospector's death.
Sergeant Preston and a U. S. Marshal trail a ruthless bone-crushing bruiser and two henchmen who are stealing tobacco in Alaska and smuggling it across the border for sale in the Yukon.
Two brothers are at odds with each other after the death of their father. Disagreement over a gold mine fuels their fighting. When a charred body is found in their burned cabin, the surviving brother is arrested.
After looting a trading post and murdering the owner, two savage profiteers use the stolen food to extort gold from the starving inhabitants of a successful mining camp that was stranded from its supply chain.
Concerned for his mother's safety, young Jimmy Greenwood leads murderous fur thieves on a dangerous chase over treacherous and little-used trails with Sergeant Preston and Constable Malloy in close pursuit.