An aspiring news photographer with a curious knack for being in the right place at the right time helps Sergeant Preston and King in their pursuit of fur thieves who were responsible for the death of an Indian brave.
Reformed ex-convict Luke Reading is accused of masterminding a series of robberies by a gang of hooded thieves, but he becomes Sergeant Preston's ally when evidence begins to point in another direction.
A ruthless member of a gambling syndicate attempts to affect the outcome of the All-Yukon Dog Race by assaulting the owner of the favored team and attempting to poison his lead dog.
Sergeant Preston offers help to an inexperienced young couple while pursuing thieves who have tapped into the RCMP's telegraph line in order to obtain confidential information concerning gold shipments.
Treacherous sneak thief Milt Strang is saved from freezing by compassionate Yukon newcomer Eileen Mabry. Strang repays the young woman's kindness by attempting to steal her husband's valuable gold claim at gunpoint.
Sergeant Preston must act quickly to prevent a lynching when struggling miner Johnny Johnson is falsely accused of murdering the man who held an overdue note on his claim.
In the Alaskan town of Skagway, Sergeant Preston is assisted by U. S. Marines in his dangerous undercover pursuit of a murderous fugitive and the head of a gold smuggling ring.
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.
While searching for a missing university professor, Sergeant Preston and the professor's son are taken captive by Kutchin Indians and face execution unless Yukon King can quickly find evidence that the Kutchins' "Totem Spirit" is a fraud.
An aging miner finds a rich lode with the help of his newly-acquired English partner, but the sudden wealth makes him the target of his envious brother-in-law and a murderous claim jumper.
Attempting to be the first to reach a new gold strike, greedy prospectors assault a trail-wise competitor, steal his coveted food cache, and cruelly leave him to die from wolves or exposure.
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.
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.
A dishonest promoter with a disdain for "Marquess of Quensberry" boxing rules schemes to abscond with the proceeds from a heavily-attended fight in the remote mining town of Wheelers.
The pusillanimous son of a crusading local newspaper publisher discovers his courage after he is abducted and threatened by the henchmen of the corrupt town boss and his dishonest attorney.
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.
A dishonest troupe of traveling performers plans to frame a former war hero for the theft of $17,000 in contributions intended for the families of the American servicemen who died as a result of the explosion of the U.S.S. Maine.
Constable Lee Wayne questions his own qualifications to serve as a Mountie when the brother of his fiancée is involved in a bank robbery and Wayne is unable to take the actions necessary to prevent his getaway.
Mine owner "Windy" Brown's braggadocio and his exaggeration of the size of a gold shipment put Sergeant Preston and King in danger from a pair of sneak thieves.
Yukon King's "lame dog" trick helps Sergeant Preston get close enough to reason with Tom Elders, a gentle veterinarian who turned into a rifle-brandishing hermit after apparently being swindled out of his life's savings of $9,000.
Sergeant Preston is close behind as young Constable Dennis Burns doggedly pursues murderous Lefty Burke across rough country, unaware that Burke is actually his long-absent father.
After his Eskimo tribe saves two white men from from freezing to death, tribe leader Ooluk vows revenge when the two decide to repay the kindness by stealing furs and assaulting Ooluk's wife and brother.
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 takes an interest when a young boy and his dog are both rescued from potentially life-threatening injuries by a man who may be a fugitive from justice.
Sergeant Preston searches rough and uncharted country for a lost party that was delivering a vital Indian treaty, but he is unaware that his "guide" is actually a saboteur who strongly opposes the treaty.
Sergeant Preston and King go on a determined mission to remote Herschel Island after receiving word that violent mutineers from a stranded whaling vessel have virtually enslaved the peaceful Eskimos who inhabit the area in winter.
Sergeant Preston poses as a cheechako in an effort to expose a pair of murderous thieves who dress in eerie all-white outfits to ambush (and frequently kill) would-be prospectors to steal their supplies.
Treachery abounds as a wealthy man's business manager murders a jewel thief in order to obtain the "Eye of Evil", a $100,000 black pearl that was stolen in the U. S. and smuggled into the Yukon in the hope of finding a buyer.
Two thieves who robbed an elderly miner meet Sergeant Preston on the trail and attempt to arrange an "accident" when King repeatedly sniffs near the stolen gold.
Bank robber Walt Daniels endangers his ex-wife and young son by returning to their home after telling his violence-prone partner Harry Evans that he must meet Daniels there in order to claim a share of the stolen money.
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.
Hyde and henchman Ram intend to take over Walker transport business. Grandpa El and Billy Walker plead for time as selling valuable pups will clear the debt. But violence occurs and Sgt. Preston chases the culprits to the Canadian border.