A young Boston woman, Kathy O'Fallon, travels north to visit her Uncle John at his cabin near the Canada–US border. While there she meets Mike Flannigan, a sergeant with the Canadian Royal North-West Mounted Police, and before long they are in love. Kathy marries Mike, who takes her by dogsled to his outpost in the cold, remote north.
Life is harsh there, particularly during the winters. A tightly knit community counts on Mike in ways that go far beyond normal police business. But he is away when a pregnant Kathy begins to worry about giving birth in such a primitive environment. Neighbors help deliver Mary, a baby girl, but surviving in the wilderness is extremely difficult, and the child dies during a diphtheria epidemic. Kathy makes up her mind to return to Boston, but realizes that she still loves and can't leave Mike.
