In 1816, a young doctor named John Polidori was offered the position as traveling physician to George Gordon, Lord Byron. Polidori was saturnine, caustic, ambitious, well-educated and handsome. He had graduated from medical school at 19 (as unusual then as now) and this offer came not a year later. Over the objections of his family, he accepted. Polidori had literary ambitions; here was an amazingly famous poet asking him to join him on a tour of the Continent. It must have felt like fate was tugging him along. In confirmation of how well things were going, a publisher offered him 500 pounds to keep a diary of his travels with [...]