Rene (Emile Genest) is a young orphan boy who takes a job at a sportsman's Canadian retreat by the St. Lawrence River. James Haggin (Walter Pidgeon) is the lonely hunter who trains hunting dogs to keep his mind off the loss of his only son. Rene is put in charge of training an incorrigible Irish setter named Big Red. The boy and the dog are separated until after a big dog show, but the overactive canine crashes through a window to be with the boy. James thinks the injured dog should be put to sleep, but Rene runs away with Red and nurses him back to health. When James becomes trapped after a fall, a menacing mountain lion looms nearby. Red must fight the ferocious feline to save the boy and the hunter. Norman Tokar directed this Walt Disney film production.