While visiting an old castle in England, Samantha and Nellie solve mysteries involving a ghost and some missing rare books.

"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. Marie-Grace and Wilhelmina have to unravel the clues...

When Marie-Grace arrives in New Orleans in 1853, she is not sure she fits in, until an unexpected invitation opens the door to friendship.

In 1935, while preparing to write a newspaper story about a theater production of Macbeth in her hometown of Cincinnati, twelve-year-old Kit discovers that a thief is stealing from the box office.

As the yellow fever epidemic continues to ravage New Orleans and the orphanages become more crowded, Marie-Grace and Cécile help with the orphans, until Marie-Grace learns that her Uncle Luc's fiancée, Mademoiselle Océane, has fallen ill.

In 1754, with her own parents taken captive, twelve-year-old Rebecca must confront her fear and hatred of the Abenaki when a boy raised by members of that tribe is brought to the fort at Charleston, New Hampshire, just before a series of thefts occurs.