Sullivan is still trapped with the Melville's Medicine Show, along with Frederick, Esmeralda and Clarence, travelling around the country. But his family has not given up hope. His parents got in touch with the parents of the other children, and his sister, Jinny, is determined to get back on the road with Manny in order to pick up the trail of the mysterious medicine show. And they are helped by a very real clue: a decades-old newspaper article about a travelling medicine show that mysteriously bears the same name ...

Back at the show, the Melvilles are becoming unhappy with the children's performances. Sullivan drops some eggs, and worse, Clarence is finding it a tighter and tighter squeeze inside the "automaton," the chess-playing Napoleon. They are soon going to need a new child to join the show, and the Melvilles know just the right one. Despite the children's best efforts to prevent another child from being kidnapped, a new girl joins the show.

But the Melvilles may have underestimated the new girl, whose feisty nature is inspirational to Sullivan. The Melvilles certainly seem preoccupied with something--at every new site, Master Melville can be seen carefully examining the grounds. With their families ever closer, the children of the travelling medicine show band together to solve the mystery of who the Melvilles really are and just what they are looking for.