American history teacher Nathan Greene looked at his bulletin board. How did Benedict Arnold become the second president of the United States? And who the heck was Shippen Jefferson? Where were John Adams and John Quincy Adams? Shaken, Greene pulled down his map of the United States. He scanned the map: no major changes."Mr. Greene," Victor Bridges called out. "Tennessee is missing!'Greene's jaw dropped. Where Tennessee had once proudly been, there was now "Franklin."Had Greene and his high school students inadvertently changed history with their field trip to the Philadelphia of 1776? There had been no such repercussions the previous spring when Greene took his class to Ford's Theater for the fateful performance of "Our American Cousin" at Ford's Theater on the evening of April 14, 1865. That spring trip had been such a success that his students fell in love with history and begged for another trip for their junior year.But somehow the Philadelphia field trip had caused a "butterfly effect" in the historical timeline evicting John Adams and John Quincy from the White House and erasing the prominence of the Adams family from American history. The ghost of Harvard Historian Henry Brooks Adams, great-grandson of John Adams, was pitching a fit and now Greene was facing an inquiry by a panel of dead historians led by Thucydides himself. Greene was beginning to rue the day he purchased a strange box at a rummage sale at the Cassadaga Hotel, the cosmic center of Cassadaga, Florida, "The Psychic Capital of the World," and home to scores of psychics and mediums and a plethora of phantasms, including an overabundance of the ghosts of forgotten historians from Henry Adams to Howard Zinn.How was Greene to know that the box he bought was a duplicate of Pandora's? How was he to know that the box contained Nikola Tesla's prototype for a time travel device that jealous rival Thomas Alva Edison had stolen from the Serbian-born inventor and hidden in the basement of the Cassadaga Hotel shortly after "The Wizard of Menlo Park" received an honorary degree from nearby Rollins College in February of 1930? Tesla's assembly instructions were a snap to follow, and the initial field trip had gone so well that Greene decided to try a fall field trip to colonial Philadelphia. But something had gone wrong; what had they done? Therein lies the tale.