Jillian and Everett's wedding plans are upended when fellow time-traveler Dr. Duval steps out of the shadows and into their lives. Removing the Eiffel Tower as part of an experiment, Duval inadvertently creates a new timeline where the United States of America disappears in 1804 and is replaced by a French monarchy. Duval may not care whether America is a kingdom or a democracy, but he'll stop at nothing to understand how spacetime operates. Desperate for information he needs, Duval hunts down Dr. Littlewood. Jillian and Everett's wedding is on hold, and before long their lives are in danger. To stop Duval, Everett secretly travels to 1802 where he is jailed in the famed Conciergerie prison as an English spy. Jillian has a terrible choice. Will she play it safe in the American kingdom she knows, or will she travel to 1802 to alter history and save Everett from the guillotine?