John Keith Dennis Morgan is wrongly convicted of murdering Roger Cass in the frontier town of River's End, Alberta, during the early 1900s. After being sentenced to hang, Keith makes a daring escape from custody, and his French-Canadian friend, Andy Dijon George Tobias, is ready with a canoe and supplies as Keith heads north into the harsh wilderness alone.
Sergeant Derry Conniston Dennis Morgan, newly arrived from the Fort McMurray detachment, is ordered by Inspector McDowell James Stephenson of the Royal Northwest Mounted Police to track and arrest Keith. For fourteen months, Conniston relentlessly follows Keith across a sweeping landscape that stretches from Saskatchewan and Manitoba to the vast Northwest Territories, driven by a sense of duty and the hope of vindicating the innocent man.
Near the Mackenzie River, after Keith has carved out a remote wintering life in a snowswept cabin, he finds Conniston unconscious in the snow with a broken leg and exposure. He tends to the injured Mountie for weeks, nursing him back to health. Keith shaves off his beard, and Conniston is struck by how closely they resemble each other. With the Mountie still near death, Conniston urges Keith to take his place in River's End and uncover the real murderer.
Keith is skeptical at first, but the arrival of the constables Jeffers John Ridgely and Kentish Frank Wilcox, who have been sent to locate Conniston, shifts the balance. They assume Keith is the Mountie, and when the dying Conniston declares that he is Keith, the deception is cemented.
Returning to River's End in the guise of the late Sergeant Conniston, Keith is granted permission to reopen the murder case. He suspects the murdered man's business partner, Norman Talbot Victor Jory, who lied at the trial, and who is friendly enough to probe for anything that could incriminate him and his associates, Balt David Bruce and Crandall Edward Pawley. Keith conceals his suspicions and keeps Talbot at ease.
Keith confides in his friend Andy Dijon, but others fall for his imposture. Even Linda Conniston Elizabeth Inglis is fooled—she has come to town for a visit, having not seen her brother for six years. Keith is unsettled when a romance blossoms between Linda and Talbot, adding personal stakes to the investigation.
During a barn dance, Andy overhears Talbot chastising Crandall for drinking and talking too much. To widen the rift, Andy provokes Crandall into a saloon brawl, giving Keith an excuse to jail Crandall. Keith convinces Crandall that he is a suspect in the Cass murder and urges him to betray Talbot to save himself.
Linda and Talbot announce they will marry and leave town soon. Desperate for Linda to reconsider, Keith reveals the truth, but she is shaken to learn that her brother is dead and suspects Keith of murder.
Back before Inspector McDowell, Keith admits his deception, yet Constables Jeffers and Kentish confirm that he did not kill Conniston, and an ensuing confession from Crandall implicates Talbot as the man who murdered Cass in a business dispute.
Talbot is arrested as he tries to flee with Linda, and the Mounties close in. It is ultimately Keith, not Talbot, who helps bring the culprit to justice. Talbot is tried, convicted, and sentenced to hang. Linda receives a medal on behalf of her late brother, and Andy marries his long-suffering girlfriend, Cheeta [Steffi Duna]. The two newlyweds depart for their honeymoon by canoe, with Cheeta playfully questioning whether Andy truly measures up — a light note that ends with a wry compliment about his unique, if blunt, character. As they paddle away, Cheeta may flirt with trouble, but she remains certain that French Canadians do not make poor papas, a joke that underlines the stubborn vitality of the town and its people. The story closes on River’s End’s gentle, stubborn optimism as the pair drift toward the horizon, waving goodbye to Linda and John.
