Man & Beast by Michael Jensen

What is the line that separates man from beast?

The year is 1797, and 24-year-old John Chapman is lost on the American frontier with winter falling fast. Near death, he stumbles upon a lone cabin, and the owner, a rugged but sexy frontiersman named Daniel McQuay, agrees to let John winter over. John and Daniel quickly find themselves drawn to each other, the sex between them unlike anything John has ever known. But as the weeks turn into snowbound months, Daniel begins to change into someone brutish, and the line between man and beast disappears.

With the arrival of spring, John flees, eventually finding refuge in the company of a group of frontier outcasts, including a brash young settler named Palmer. But in the wilds of this savage land, love is not so easily tamed, and John soon finds himself calling upon the raging animal within him to save the man he loves.