While running from the Nazis in occupied Norway, Holger Carlson is struck unconscious, and awakens in an alternate Earth. In this Earth, it is still the medieval period, and the forces of Law and Chaos are locked in a life and death struggle. Lawful humans seem to believe that Holger is a great knight-errant, who will carry the battle to the Chaotic elves.
This wonderful fantasy book was written one year before Tolkien's Lord of the Rings (and 16 years after The Hobbit), and was a major influence on the original Dungeons and Dragons role-playing game. It is a great adventure, and quite a view into the early history of modern fantasy literature. This is a great book, and I recommend it wholeheartedly.