Tom "Wolf" Lowry, the owner of the Bar Z ranch, tolerates no intruders into his life. When he hears that settlers have entered his valley, he goes to confront them but has a change of heart when he sees Mary Davis, a young woman who has come West to find her missing sweetheart, Owen Thorpe. Mary nurses Lowry back to health after he is wounded by Buck Fanning, the real estate agent who sold Mary her claim, when Lowry prevents Banning from raping Mary. Lowry soon falls in love with Mary and she agrees to become his wife, having lost all hope of finding her former sweetheart. By coincidence, Lowry finds Owen, but when Owen and Mary meet and plan to run away together, Lowry insists that she honor her agreement to wed him. On the day of the wedding, however, Lowry has a change of heart and takes Owen and Mary to the minister and tells him to marry the two lovers instead. Lowry then leaves Mary a note saying that he is going to Alaska. Five years later, Mary and Owen are the parents of a young son, named Tom, and the recipients of a letter from Lowry who now lives in isolation in Alaska.