When Marie-Grace discovers a baby outside her father's office and a slave catcher claims the boy, she helps place him at a white orphanage where she becomes a volunteer, as her friendship with Cécile grows and she hears rumors of yellow fever.
Marie-Grace Gardner, a doctor's daughter who has just returned to her native New Orleans in 1853, makes friends with Cécile Rey, whose prosperous family are free people of color, and is persuaded to change places with her at separate Mardi Gras balls.
"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 an archaeologist's priceless jewel goes missing during a 1906 ocean liner voyage to Europe, eleven-year-old Samantha tries to discover which of the first-class passengers is the thief. Includes French glossary and historical information on travel and archaeology in the early twentieth century.
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.
When her family temporarily moves into a luxury apartment building in 1904 Manhattan, eleven-year-old Samantha tries to discover whether a series of mishaps is related to a curse on the building's owner.
Marie-Grace is excited that a well-known English opera company will perform at the very theater where she takes singing lessons from Aunt Océane, but as she and her friend Cécile help out backstage, the make disturbing discoveries.