After Francie Wolcott's parents die in a carriage crash, leaving her and her genius younger brother, Rooney, penniless, she intends to tour the world with the fortunetelling automaton he built. But first she must bring Rooney to their uncle in San Francisco, where he will have a place to happily tinker and invent things.

With no traveling funds, Francie and Rooney join a traveling carnival heading west, using the automaton as an attraction to pay their way. All goes well at first—then she finds out big the world is and how complicated it really is.