Successful Canadian soprano Marie de Flor (Jeanette MacDonald) is informed by a man named Boniface (George Regas) that her brother, Jack Flower (James Stewart), has apparently escaped from prison and killed a Mountie. Marie and Boniface depart for the Canadian wilderness to locate and help Jack. Meanwhile, Sergeant Bruce (Nelson Eddy) of the Mounties is tasked with finding Jack. When Marie and Boniface reach Lake Chibougamau, near where Jack is reportedly hiding, Boniface takes Marie's money and leaves her on her own. She falls in with Sgt. Bruce but doesn't admit to her relationship to Jack. However, Bruce recognizes her through the sound of her singing voice. Marie eventually locates Boniface again and they leave together to search for Jack, with Bruce in pursuit of them. Bruce rescues Marie from drowning in a river and Boniface flees again. Marie reluctantly accepts Bruce's help as they both realize that they are in love with each other. Marie notices Bruce's singing skills and tries to convince him to quit the Mounties and start a singing career, which Bruce declines. They part ways again and Marie reunites again with Boniface, who takes her to Jack, who has been cared for by Boniface's mother. But Bruce has continued to follow and is determined to fulfill his duty and arrest Jack.
—Patrick Depew