A bump on the head sends Hank Martin, 1912 mechanic, to Arthurian Britain, 528 A.D., where he is befriended by Sir Sagramore le Desirous and gains power by judicious use of technology. He and Alisande, the King's niece, fall in
Harry Potter and the Chamber of Secrets
Harry Potter and the Prisoner of Azkaban
Harry Potter and the Deathly Hallows: Part 2
Harry Potter and the Goblet of Fire