The Devil Behind Me — Frederick E. Smith

The Hunter is an implacable enemy determined to kill - the Hunted are Austrian pair, Anna and Carl Frandl and John Drayton, the English holidaymaker who has rather rashly befriended them. The setting is Sweden and the mysterious tundra of Lapland, a place so eerie and primitive that civilised laws seem to be suspended, and replaced by the oldest law in the world - kill or be killed.