On a dark and stormy night, a book collector shows Mortensen the prize of his collection: an illuminated manuscript from 1512. When Mortensen sees a painting of an airplane on one of its pages, he knows he has a mystery to unravel. With a zap from his time gun, he travels back to medieval Scotland to look for clues. A wise scribe and a mute witch help him on his adventure, but neither of them can answer his question: how did an airplane crash land in the Middle Ages?
