Renegades among the Tumbleweeds
Hewitt Freiburg, author
A wealthy Japanese businessman receives a series of posthumous letters and materials from a longtime friend and Cambridge college mate, who was Welsh and a scholar of medieval Welsh history. The materials suggest that a Welsh sea captain might have arrived at the eastern coast of what is now the United States in the 1300s. He suggests his Japanese friend investigate, and the next thing you know, you're in the middle of the Holy Roman Empire.