"Marie-Grace can't wait to begin her journey up the Mississippi River with her father. The steamboat they're traveling on is the biggest and fanciest boat Marie-Grace has ever seen. It's crowded with all sorts of interesting passengers, including Wilhelmina Newman, a girl her age. Wilhelmina is traveling alone, and she's carrying a secret in one of her trunks--clues to hidden Gold Rush treasure."--Provided by publisher.