Dr. Bill Crawford, on a hunting trip to Canada, is attacked by a bear and his guide, Joe Easter, saves his life and takes the badly-mauled Crawford to his cabin home, where he lives with his beautiful young wife, Alverna. Leaning Bill there to recover, Joe goes on a prolonged hunting trip and Bill and Alverna fall in love. The local doctor, Billar, dies during an operation which Bill completes and then decides to remain in Lost Lake and continue his practice there...close to Alverna. The lovers decide that, in fairness to Joe, Bill must return to his former city. But an epidemic of streptococcus breaks out in the Lost Lake village. Bill, untrained in the ways of the primeval woods, sets out in a raging blizzard, in search of the messenger who had been sent to the nearest town for a special serum needed to break the epidemic. Fearing for his life, Alverna follows him and they find the messenger dead in his automobile, with the serum by his side. Exhausted they stagger into a deserted cabin and drowse into unconsciousness. Meanwhile, Joe, back from his hunting trip, is persuaded by the village gossips that his wife has run off with Bill. He starts after them, in his dog-sled, with murder in his heart.